Methods and apparatus for knee arthroplasty

ABSTRACT

Methods and apparatus for knee arthroplasty, including implants, positioning and alignment guides, cutting guides, cutting tools and techniques for the femur and/or tibia.

PRIORITY APPLICATIONS

This application is a continuation of co-pending U.S. application Ser.No. 10/756,817, which is a continuation of U.S. application Ser. No.09/799,325 filed Mar. 5, 2001, now U.S. Pat. No. 6,695,848. The entiredisclosures of these priority applications are expressly incorporatedherein by reference.

RELATED APPLICATIONS AND PATENTS

This application is related to co-pending U.S. application Ser. Nos.10/756,817, 10/958,203, and 10/967,673, all of which are assigned to theassignee of the present application and the entire disclosure of each ofwhich is expressly incorporated herein by reference. This application isalso related to U.S. Pat. Nos. 6,197,064, 5,879,354, 5,810,827,5,755,803, 5,643,272, 5,597,379, and 5,514,139, all of which areassigned to the assignee of the present application and the entiredisclosures of each of which are expressly incorporated herein byreference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention generally relates to methods and apparatus for kneearthroplasty, including implants, guides, tools and techniques for thefemur and/or tibia.

2. Related Art

Different methods and apparatus have been developed in the past toenable a surgeon to remove bony material to create specifically shapedsurfaces in or on a bone for various reasons including to allow forattachment of various devices or objects to the bone. Keeping in mindthat the ultimate goal of any surgical procedure is to restore the bodyto normal function, it is critical that the quality and orientation ofthe cut, as well as the quality of fixation, and the location andorientation of objects or devices attached to the bone, is sufficient toensure proper healing of the body, as well as appropriate mechanicalfunction of the musculoskeletal structure.

In total knee replacements, a series of planar and/or curvilinearsurfaces, or “resections,” are created to allow for the attachment ofprosthetic or other devices to the femur, tibia and/or patella. In thecase of the femur, it is common to use the central axis of the femur,the posterior and distal femoral condyles, and/or the anterior distalfemoral cortex as guides to determine the location and orientation ofdistal femoral resections. The location and orientation of theseresections are critical in that they dictate the final location andorientation of the distal femoral implant. It is commonly thought thatthe location and orientation of the distal femoral implant are criticalfactors in the success or failure of the artificial knee joint.Additionally, with any surgical procedure, time is critical, and methodsand apparatus that can save operating room time, are valuable. Pastefforts have not been successful in consistently and/or properlylocating and orienting distal femoral resections in a quick andefficient manner.

The use of oscillating sawblade based resection systems has been thestandard in total knee replacement for over 30 years. Due to their useof this sub-optimal cutting tool, the instrumentation systems allpossess certain limitations and liabilities.

Perhaps the most critical factor in the clinical success of TKA is theaccuracy of the implant's placement. This can be described by thedegrees of freedom associated with each implant; for the femoralcomponent these include location and orientation that may be describedas Varus-Valgus Alignment, Rotational Alignment, Flexion-ExtensionAlignment, A-P location, Distal Resection Depth Location, andMediolateral Location. Conventional instrumentation very often relies onthe placement of ⅛ or 3/16 inch diameter pin or drill placement in theanterior or distal faces of the femur for placement of cutting guides.In the case of posterior referencing systems, the distal resectioncutting guide is positioned by drilling two long drill bits into theanterior cortex. As these long drills contact the oblique surface of thefemur they very often deflect, following the path of least resistanceinto the bone. As the alignment guides are disconnected from thesecutting guides, the drill pins will “spring” to whatever position wasdictated by their deflected course thus changing their designated,desired alignment to something less predictable and/or desirable. Thiskind of error is further compounded by the “tolerance stacking,”inherent in the use of multiple alignment guides and cutting guides.Another error inherent in these systems further adding to mal-alignmentis deflection of the oscillating sawblade during the cutting process.The use of an oscillating sawblade is very skill intensive as the bladewill also follow the path of least resistance through the bone anddeflect in a manner creating variations in the cut surfaces whichfurther contribute to prosthesis mal-alignment as well as poor fitbetween the prosthesis and the resection surfaces. Despite the fact thatthe oscillating saw has been used in TKA for more than 30 years,orthopedic salespeople still report incidences where poor cuts result insignificant gaps in the fit between the implant and the bone.

It is an often repeated rule of thumb for orthopedic surgeons that a“Well placed, but poorly designed implant will perform well clinically,while a poorly placed, well designed implant will perform poorlyclinically.” One of the primary goals of the invention described hereinis to eliminate errors of this kind to create more reproducible,consistently excellent clinical results in a manner that requiresminimal manual skill on the part of the surgeon.

None of the previous efforts of others disclose all of the benefits andadvantages of the present invention, nor do the previous efforts ofothers teach or suggest all the elements of the present invention.

OBJECTS AND SUMMARY OF THE INVENTION

Many of the specific applications of the method and apparatus of thepresent invention described herein apply to total knee replacement, asurgical procedure wherein planar surfaces and/or curvilinear surfacesmust be created in or on bone to allow for proper attachment orimplantation of prosthetic devices. However, it should be noted that itis within the scope of the present invention to apply the methods andapparatus herein described to the removal of any kind of material frombones in any other application where it is necessary, desirable oruseful to remove material from bones.

The apparatus of the present invention comprises a number of componentsincluding a positioning apparatus, a pattern apparatus and a cuttingapparatus.

The pattern apparatus is oriented and located by the use of thepositioning apparatus which references the geometry of a bone to beresected and/or other anatomic landmarks. When used to resect a distalfemur, the positioning apparatus also references the long axis of thefemur. Once the positioning apparatus has been properly located,aligned, and initially fixed in place, the pattern apparatus may beattached thereto, and then adjusted according to the preferences of thesurgeon utilizing the apparatus, and then the pattern apparatus can berigidly fixed to a bone to be resected. This ensures the patternapparatus is properly located and oriented prior to the use of thecutting apparatus to remove material from the bone.

More specifically, when the method and apparatus of the presentinvention are used in connection with resecting a distal femur, thepositioning apparatus is located and aligned utilizing theintramedullary canal of the femur, (thereby approximating the long axisof the femur), the distal surfaces of the femoral condyles, the anteriorsurface of the distal femur, and the posterior surfaces of the femoralcondyles, which are referenced to indicate the appropriate location andorientation of the pattern apparatus. Fixation means may be used to fixthe positioning apparatus, as well as the pattern apparatus to thedistal femur. Means may be present in the positioning apparatus and/orpattern device for allowing the following additional adjustments in thelocation and orientation of the pattern device:

1. internal and external rotational adjustment;

2. varus and valgus angular adjustment;

3. anterior and posterior location adjustments;

4. proximal and distal location adjustment; and

5. flexion and extension angular adjustment.

Cannulated screws, fixation nails or other fixation means may then beused to firmly fix the pattern apparatus to the distal femur. Thepositioning apparatus may then be disconnected from the patternapparatus and removed from the distal femur. Thus, the location andorientation of the pattern apparatus is established.

The pattern device possesses slot-like features, or a cutting path,having geometry that matches or relates to the desired geometry of thecut. When used in connection with resecting a knee, the cutting pathresembles the interior profile of the distal femoral prosthesis. Thecutting path guides the cutting apparatus to precisely and accuratelyremove material from the distal femur. Thus, the distal femur is therebyproperly prepared to accept a properly aligned and located distalprosthesis.

In preparing a patella, the pattern device may be an integral part ofthe positioning apparatus which is oriented and located by referencingthe geometry of the patella itself as well as the structures of thepatellofemoral mechanism to determine the location and orientation of apredominantly planar resection. The cutting device may then be employedto perform the resection of the patella by traversing the path dictatedby the pattern device, thus dictating the final location and orientationof the patella prosthesis.

The apparatus of the present invention comprises a number of componentsincluding an ankle clamp, an alignment rod, a fixation head, cuttingguide clamps having an integral attachment mechanism, and a milling bit.

The method of present invention includes the steps of attaching theankle clamp about the ankle, interconnecting the distal end of thealignment rod with the ankle clamp, interconnecting the fixation headwith the proximal end of the alignment rod, partially attaching thefixation head to the proximal tibia, aligning the alignment rod,completely attaching the fixation head to the proximal tibia,interconnecting the cutting guide clamps with the alignment rod,positioning the cutting guide clamps about the proximal tibia, securingthe cutting guide clamps to the tibia at a proper location, removing thefixation head, and cutting the proximal tibia with the milling bit.

The implant of the present invention has an outer bearing surface and aninner attachment surface. The outer bearing surface functions as a jointcontact surface for the reconstructed bone. The inner attachment surfacecontacts a bone and is attached thereto. The inner attachment surface ofthe implant is curvilinear from an anterior to a posterior area of thefemur, as is conventionally known, and is also curvilinear from a medialto a lateral area of the femur to approximate the shape of naturalfemur. The resection of the femur for accommodating the implant can beproperly performed by a milling device employing one or more curvilinearmilling bits.

There are numerous advantages associated with the curvilinear implant ofthe present invention. First, it will allow for a very thin implantcross-section and therefore necessitate the removal of the least amountof viable osseous tissue. Accordingly, the kinematics of the artificialjoint could be made to be as close as possible to that of a healthy,natural knee joint. In addition, the curvilinear geometry of the implantdramatically decreases the stress risers inherent in conventionalrectilinear femoral implants and allows for a thinner cross-sectionalgeometry while potentially increasing the resistance of the implant tomechanical failure under fatigue or impact loading. Conversely, thecurvilinear geometry of the implant may also allow for an advantageousreduction in the flexural rigidity of the implant which may result inavoidance of the “stress-shielding” inherent in rigid implant designs.

This curvilinear implant of the present invention could also result in aless expensive femoral implant because of the reduced amount of materialneeded for the implant, as well as an improved, more natural, and evenstronger knee replacement. The cross-section of the implant could bevaried to assist in seating the implant and to increase the strength andfit of the implant. The implants of the present invention havingcurvilinear implant surfaces could be fabricated of metal, plastic, orceramic or any other material. Further, the thickness of the implantsand the material required to fabricate the implant could be reduced asthe implants are adapted to increasingly curvilinear surfaces.

The resected surfaces of a femur or other bone to accept the implant ofthe present invention could be prepared by the apparatus and method forresection shown and described in the prior related applications setforth herein, the entire disclosures of which are expressly incorporatedherein by reference.

The apparatus of the present invention comprises a number of componentsincluding a positioning and drill guide, a cutting guide and a cuttingapparatus. The drill guide is used to create holes in the medial andlateral sides of the femur that correspond to the fixation features ofthe cutting guide. The cutting guide is oriented and located byinserting fixation nubs connected to the cutting guide into the medialand lateral holes in the femur. The cutting guide can then be furtheraffixed to the femur. The cutting apparatus can then be used with thecutting guide to resect the femur. A conventional cutting block usedwith a conventional oscillating saw can also be positioned andinterconnected with a femur in a similar manner using the drill guide ofthe present invention to create medial and lateral holes. A cuttingguide can then be attached to the holes. A conventional cutting blockcan be interconnected with the cutting guide for attachment of the blockto the femur. This invention can also be used in connection with acortical milling system, i.e., a cutting system for providing acurvilinear cutting path and curvilinear cutting profile. Likewise, atibial cutting guide can similarly be positioned on a tibia with a drillguide.

It is a primary object of the present invention to provide an apparatusfor properly resecting the distal human femur.

It is also an object of this invention to provide an apparatus forproperly orienting a resection of the distal human femur.

It is an additional object of the resection apparatus of the presentinvention to properly locate the resection apparatus with respect to thedistal human femur.

It is even another object of the resection apparatus of the presentinvention to properly orient the resection apparatus with respect to thedistal human femur.

It is another object of the resection apparatus of the present inventionto provide a guide device for establishing the location and orientationof the resection apparatus with respect to the distal human femur.

It is still a further object of the resection apparatus of the presentinvention to lessen the chances of fatty embolisms.

It is even a further object of this invention is to provide a resectionapparatus capable of forming some or all of the resected surfaces of thedistal human femur.

It is another object of the resection apparatus of the present inventionto provide an apparatus which is simple in design and precise andaccurate in operation.

It is also an intention of the resection apparatus of the presentinvention to provide a guide device for determining the location of thelong axis of the femur while lessening the chances of fatty embolism.

It is also an object of the resection apparatus of the present inventionto provide a device to physically remove material from the distal femurin a pattern dictated by the pattern device.

It is even another object of the resection apparatus of the presentinvention to provide a circular cutting blade for removing bone from thedistal human femur to resection the distal human femur.

It is also an object of the present invention to provide a method foreasily and accurately resecting a distal human femur.

These objects and others are met by the resection method and apparatusof the present invention.

It is a primary object of the present invention to provide methods andapparatus for femoral and tibial resection.

It is another object of the present invention to provide a method andapparatus for properly, accurately and quickly resecting a bone.

It is also an object of this invention to provide a method and apparatusfor properly orienting and locating a resection of a bone.

It is a further object of the present invention to provide a method andapparatus to properly locate and orient the resection apparatus withrespect to a bone.

It is another object of the present invention to provide methods andapparatus for femoral and tibial resection which are simple in designand precise and accurate in operation.

It is an additional object of the present invention to provide a methodand apparatus to physically remove material from a bone in a patterndictated by a pattern device and/or the geometry of a cutting device.

It is a further object of the present invention to provide methods andapparatus for resecting a bone which allows one to visually inspect thelocation of the cut or cuts prior to making the cut or cuts.

It is yet a further object of the present invention to provide a methodand apparatus for resecting a bone which physically removes materialfrom the bone along a surface dictated by a guide device.

It is still a further object of the present invention to provide amethod and apparatus for resecting a bone which employs a milling bit orform cutter for removing material from the bone.

It is a further object of the present invention to provide methods andapparatus for femoral and tibial resection wherein the apparatus can belocated on a bone to be cut in a quick, safe and accurate manner.

It is a primary object of the present invention to provide a method andapparatus for properly resecting the proximal human tibia in connectionwith knee replacement surgery.

It is also an object of the present invention to provide a method andapparatus for resecting the proximal human tibia which minimizes theskill necessary to complete the procedure.

It is another object of the present invention to provide a method andapparatus for resecting the proximal human tibia which properly orientsthe resection of the proximal tibia.

It is even another object of the present invention to provide a methodand apparatus for resecting the proximal human tibia which is easy touse.

It is yet another object of the present invention to provide a methodand apparatus for resecting the proximal human tibia which orients theresection in accordance with what is desired in the art.

It is still yet another object of the present invention to provide amethod and apparatus for resecting the proximal human tibia whichminimizes the amount of bone cut.

It is a further object of the present invention to provide a method andapparatus for resecting the proximal human tibia which allows one tovisually inspect the location of the cut prior to making the cut.

It is even a further object of the present invention to provide a methodand apparatus for resecting the proximal human tibia which is simple indesign and precise and accurate in operation.

It is yet a further object of the present invention to provide a methodand apparatus for resecting the proximal human tibia which physicallyremoves material from the proximal tibia along a surface dictated by aguide device.

It is still a further object of the present invention to provide amethod and apparatus for resecting the proximal human tibia whichemploys a milling bit for removing material from the proximal tibia.

It is also an object of the present invention to provide a method andapparatus for resecting the proximal human tibia which includes acomponent which is operated, and looks and functions, like pliers orclamps.

It is even another object of the present invention to provide analternate embodiment of the method and apparatus for resecting theproximal human tibia which includes a component that resembles aU-shaped device for placing about the tibia.

It is even a further object of the present invention to provide analternate embodiment of the method and apparatus for resecting theproximal human tibia which includes a component that resembles anadjustable, square, U-shaped device for placing about the tibia.

These objects and others are met and accomplished by the method andapparatus of the present invention for resecting the proximal tibia.

It is a primary object of the present invention to provide a method andapparatus for removing material from bones.

It is another object of the present invention to provide a method andapparatus for properly resecting bone.

It is also an object of this invention to provide a method and apparatusfor properly orienting a resection of a bone.

It is a further object of the present invention to provide a method andapparatus to properly orient the resection apparatus with respect to abone.

It is an additional object of the present invention to provide a methodand apparatus for properly locating a bone resection.

It is a further object of the present invention to provide a method andapparatus to properly locate the resection apparatus with respect to abone.

It is even another object of the resection apparatus of the presentinvention to provide a guide device and method of use thereof forestablishing the location and orientation of the resection apparatuswith respect to a bone.

It is an additional object of the present invention to provide a methodand apparatus for making a curvilinear bone resection.

It is still a further object of the resection apparatus of the presentinvention to lessen the chances of fatty embolisms.

It is even further object of this invention to provide a method andapparatus capable of forming or re-forming some or all of the surfacesor resected surfaces of a bone.

It is another object of the present invention to provide a method andapparatus which is simple in design and precise and accurate inoperation.

It is also an intention of the present invention to provide a method andapparatus for determining the location of the long axis of a bone whilelessening the chances of fatty embolisms.

It is also an object of the present invention to provide a method andapparatus to physically remove material from a bone in a pattern.

It is an additional object of the present invention to provide a methodand apparatus to physically remove material from a bone in a patterndictated by a pattern device and/or the geometry of a cutting device.

It is even another object of the resection apparatus of the presentinvention to provide a cylindrical or semi-cylindrical cutting deviceand method of use thereof for removing material from a bone.

It is also an object of the present invention to provide a method andapparatus for easily and accurately resecting a bone.

It is also an object of the present invention to provide a method andapparatus for resecting a bone which minimizes the manual skillnecessary to complete the procedure.

It is even another object of the present invention to provide a methodand apparatus for resecting a bone which is easy to use.

It is still yet another object of the present invention to provide amethod and apparatus for resecting a bone which minimizes the amount ofbone removed.

It is a further object of the present invention to provide a method andapparatus for resecting a bone which allows one to visually inspect thelocation of the cut or cuts prior to making the cut or cuts.

It is yet a further object of the present invention to provide a methodand apparatus for resecting a bone which physically removes materialfrom the bone along a surface dictated by a guide device.

It is still a further object of the present invention to provide amethod and apparatus for resecting a bone which employs a milling bit orform cutter for removing material from the bone.

It is even another object of the present invention to provide a methodand apparatus for removing material from a bone such that both thecutting path and cutting profile are predominantly curvilinear.

It is a primary object of the present invention to provide an apparatusto properly replace damaged bony tissues.

It is also an object of this invention to provide an apparatus toproperly replace damaged bony tissues in joint replacement surgery.

It is also an object of the present invention to provide an implant forthe attachment to a distal femur in the context of knee replacementsurgery.

It is an additional object of the present invention to provide a methodand apparatus for making a curvilinear implant.

It is another object of the present invention to provide an implanthaving a reduced thickness to reduce the amount of material required tomake the implant.

It is even another object of the present invention to provide an implanthaving curvilinear fixation surfaces for increasing the strength of theimplant.

It is another object of the present invention to provide an implanthaving a fixation surface that is anterior-posterior curvilinear andmediolateral curvilinear.

It is another object of the present invention to provide an implant thathas a fixation surface that is shaped to resemble a natural distalfemur.

It is also an object of the present invention to provide an implantapparatus for allowing proper patellofemoral articulation.

It is a further object of the present invention to provide for minimalstress shielding of living bone through reduction of flexural rigidity.

It is an additional object of the present invention to provide animplant apparatus having internal fixation surfaces which allow forminimal bony material removal.

It is another object of the present invention to provide an implantapparatus with internal fixation surfaces that minimize stress risers.

It is another object of the present invention to provide an implantapparatus having internal fixation surfaces for precise fixation tocurvilinear body resections.

It is another object of the present invention to provide an implantapparatus having internal fixation surfaces for precise apposition tocurvilinear body resections.

It is another object of the present invention to provide an implantapparatus having internal fixation surfaces for curvilinear interiorfixation geometries closely resembling the geometry of the external orarticular geometry of the implant apparatus.

It is also an object of this invention to provide a method and apparatusfor properly locating and orienting a prosthetic implant with respect toa bone.

It is another object of the present invention to provide an implantwhich is simple in design and precise and accurate in operation.

It is also an object of the present invention to provide an implantwhich minimizes the manual skill necessary to complete the procedure.

It is still yet another object of the present invention to provide animplant which minimizes the amount of bone removed.

It is even another object of the present invention to provide a methodand apparatus for removing material from a bone such that both thecutting path and cutting profile are predominantly curvilinear.

It is a primary object of the present invention to provide an apparatusfor properly resecting the distal human femur.

It is also an object of this invention to provide an apparatus forproperly orienting the resections of the distal human femur.

It is also an object of the present invention to provide an alignmentguide apparatus for properly orienting and locating some or all of thedistal femoral resections necessary in human total knee arthroplasty.

It is an object of the alignment guide apparatus of the presentinvention to provide a means for directly or indirectly establishing theproper orientation cutting guide devices for performing distal femoralresections.

It is even an additional objective of the alignment guide apparatus ofthe present invention to provide a means for directly establishing theproper location of cutting guide devices used to perform distal femoralresections.

It is also an object of the present invention to provide an extensionblock for determining the gap between a resected proximal tibia and aresected or unresected distal-most surface of the human femur inextension and to allow for appropriate ligament balancing.

It is an additional object of the present invention to provide anextension block for adjusting and balancing the gap between a resectedproximal tibia and an unresected or partially resected distal femur.

It is another object of the alignment guide apparatus to provide analignment device which references the resected surface of the proximaltibia to indicate the proper location and orientation of the device(s)used to guide the cutting devices used to perform the distal femoralresections.

It is another object of this invention to provide an apparatus which issimple in the design and precise and accurate in operation.

These objects and others are met by the femoral resection alignmentmethod and apparatus of the present invention. This apparatus comprisesa number of components including a guide body component, an extensionblock component, a rotating arm component, an extension rod component,and a tibial referencing component. The guide body component contactsthe distal-most surface of the femur. Its location is based off of theposterior femoral condyles and the surface of the distal-most femoralresection or the unresected distal-most femoral surface. The rotatingarm component is interconnected with the guide body and may rotate withrespect thereto, thus allowing for the direct or indirect adjustment ofthe rotating alignment of cutting guides for resecting the distal femur.In one embodiment, the rotating arm component carries arms with drillscrew apertures which direct placement of drill holes in the femur whichare used to attach a cutting guide to the femur. In another embodimentthe rotating arm component extends above the femur and receives afemoral milling device as shown in U.S. patent application Ser. No.08/300,379. The rotating arm component is attached to the extension rodcomponent which extends to the tibial referencing component whichreferences the location and orientation of the proximal resected surfaceof the tibia. Thus the rotating alignment of the distal femoralprosthesis is established with respect to the orientation of theresected proximal tibial surface.

The rotational alignment of the rotating arm component is approximatelyperpendicular the rotational alignment of the extension rod component inboth Anterior/Posterior and Mediolateral planes. The extension rodcomponent contains a means for adjusting the distance between the tibialreferencing component and the rotating arm component. The rotating armcomponent is able to rotate with respect to the guide body which isfirmly fixed to the distal femur. The extension rod is firmly fixed inthe tibial referencing component which rests on the resected tibialsurface. The adjustment of the distance between the tibial referencingcomponent and the rotating arm component distracts the femur from thetibia until distraction is restricted by the collateral ligaments andother soft tissues present in the knee joint. Thus the location andorientation of the distal femoral prosthesis is properly determined withrespect to the proximal tibial resection and the soft tissue of the kneejoint.

The rotational alignment of the drill holes in the resected distal femurshould be parallel to the resected proximal tibia when equal ligamenttension is attained through the distraction of the femur from the tibia.

It is a primary object of the present invention to provide methods andapparatus for femoral and tibial resection.

It is another object of the present invention to provide a method andapparatus for properly, accurately and quickly resecting a bone.

It is also an object of this invention to provide a method and apparatusfor properly orienting and locating a resection of a bone.

It is a further object of the present invention to provide a method andapparatus to properly locate and orient the resection apparatus withrespect to a bone.

It is another object of the present invention to provide methods andapparatus for femoral and tibial resection which are simple in designand precise and accurate in operation.

It is an additional object of the present invention to provide a methodand apparatus to physically remove material from a bone in a patterndictated by a pattern device and/or the geometry of a cutting device.

It is a further object of the present invention to provide methods andapparatus for resecting a bone which allows one to visually inspect thelocation of the cut or cuts prior to making the cut or cuts.

It is yet a further object of the present invention to provide a methodand apparatus for resecting a bone which physically removes materialfrom the bone along a surface dictated by a guide device.

It is still a further object of the present invention to provide amethod and apparatus for resecting a bone which employs a milling bit orform cutter for removing material from the bone.

It is a further object of the present invention to provide methods andapparatus for femoral and tibial resection wherein the apparatus can belocated on a bone to be cut in a quick, safe and accurate manner.

These objects and others are met by the methods and apparatus forfemoral and tibial resection of the present invention. The apparatus ofthe present invention comprises a number of components including apositioning and drill guide, a cutting guide and a cutting apparatus.The drill guide is used to create holes in the medial and lateral sidesof the femur that correspond to the fixation features of the cuttingguide. The cutting guide is oriented and located by inserting fixationnubs connected to the cutting guide into the medial and lateral holes inthe femur. The cutting guide can then be further affixed to the femur.The cutting apparatus can then be used with the cutting guide to resectthe femur. A conventional cutting block used with a conventionaloscillating saw can also be positioned and interconnected with a femurin a similar manner using the drill guide of the present invention tocreate medial and lateral holes. A cutting guide can then be attached tothe holes. A conventional cutting block can be interconnected with thecutting guide for attachment of the block to the femur. This inventioncan also be used in connection with a cortical milling system, i.e. acutting system for providing a curvilinear cutting path and curvilinearcutting profile. Likewise, a tibial cutting guide can similarly bepositioned on a tibia with a drill guide.

BRIEF DESCRIPTION OF THE DRAWINGS

Other important objects and features of the invention will be apparentfrom the following detailed description of the invention taken inconnection with the accompanying drawings in which:

FIG. 1 is an exploded view of the resection apparatus of the presentinvention showing the positioning apparatus body, the angular adjustmentcomponent and the rotational alignment component.

FIG. 2 is a side plan view of the guide device of the resectionapparatus of FIG. 1 attached to a distal human femur.

FIG. 3 is an exploded view of the pattern device of the resectionapparatus of the present invention.

FIG. 4 is a side plan view of the resection apparatus shown in FIG. 2with the pattern device fixed to the distal human femur.

FIG. 5 is an exploded front view of the cutting device of the resectionapparatus of the present invention.

FIG. 6 is a top plan view of the pattern device and the cutting deviceof the resection apparatus of the present invention affixed to thedistal human femur.

FIG. 7 is a side plan view of an intermedullary rod having a helicalgroove for use with the resection apparatus shown in FIG. 1.

FIG. 8 is a partially exploded side plan view of an embodiment of thetibial resection apparatus of the present invention shown attached tothe tibia, wherein the cutting guide clamps are of a fixed size anddirectly interconnect with the alignment rod.

FIG. 9 is a top plan view of the tibial resection apparatus, shown inFIG. 8 prior to insertion of the milling bit into the apparatus.

FIG. 10 is a partially exploded side plan view of another embodiment ofthe tibial resection apparatus shown in FIG. 8, wherein the cuttingguide clamps interconnect with the alignment rod by means of a cuttingguide clamp linkage.

FIG. 11 is a side plan view of an embodiment of the cutting guide clampsshown in FIG. 8, wherein the cutting guide clamps are adjustable.

FIG. 12 is a top plan view of the cutting guide clamps shown in FIG. 11.

FIG. 13 is a perspective view of an embodiment of the tibial resectionapparatus shown in FIG. 8, showing the proximal tibial referencingstylus attached to the cutting guide clamps.

FIG. 14 is a cross-sectional view of the profile of the ends of theclamp members taken along line A-A in FIG. 12.

FIG. 15 is a cross-sectional view of the profile of the ends of thecutting guides taken along line B-B in FIG. 12, the ends of the clampsmating with the ends of the cutting guides for positioning the cuttingguides with respect to the clamps.

FIG. 16 is a perspective view of an alternate embodiment of a U-shapedcutting guide for use in the present invention.

FIG. 17 is a top plan view of another alternate embodiment of a squareU-shaped cutting guide for use in the present invention.

FIG. 18 is a perspective view of another alternate embodiment of apartial cutting guide for use in the present invention when the patellartendon, patella, or quad tendon interferes with placement of the cuttingguide about the tibia.

FIG. 19 is a rear perspective view of an embodiment of the patternapparatus of the present invention.

FIG. 20 is a front perspective view of the pattern apparatus shown inFIG. 19.

FIG. 21 is a partially exploded side plan view of the positioningapparatus shown in FIG. 19.

FIG. 22 is an exploded perspective view of the cross-bar of the patternapparatus shown in FIG. 19.

FIG. 23 is a partially cut away side plan view of the patternplate/cross-bar attachment linkage for interconnecting the pattern plateto the cross-bar as shown in FIG. 19.

FIG. 24 is a perspective view of the positioning apparatus of thepresent invention.

FIG. 25 is a top plan view of the positioning apparatus shown in FIG.24.

FIG. 26 is an exploded perspective view of the positioning apparatusshown in FIG. 24.

FIG. 27 is an exploded perspective view of the protractor rod guideassembly portion of the positioning apparatus shown in FIG. 24.

FIGS. 28A-28D are plan views of another embodiment of a rod guideassembly for use with the positioning apparatus shown in FIG. 24.

FIG. 29 is a side plan view of an embodiment of the fixation device foraffixing the pattern apparatus shown in FIG. 19 to a bone.

FIG. 30 is a partial side plan view of the pattern apparatus shown inFIG. 19, showing the posterior/anterior referencing guide.

FIG. 31 is a side plan view of another embodiment of the patternapparatus shown in FIG. 19.

FIG. 32 is a side plan view of another embodiment of the positioningapparatus shown in FIG. 24 for use in performing ligament balancing;FIGS. 32A and 32B are cross-sectional views along section A-A in FIG.32.

FIGS. 33A and B are front plan views of an embodiment of the cuttingapparatus of the present invention for cutting a bone a in curvilinearcross-sectional plane.

FIG. 34 is a perspective view of a handle for guiding a milling bitalong a cutting path.

FIG. 35 is a perspective view of another embodiment of the patternapparatus shown in FIG. 19, having a milling bit engaged therewith.

FIG. 36 is a side plan view of the pattern apparatus shown in FIG. 35with the milling bit disengaged from the pattern apparatus.

FIG. 37 is another side plan view of the pattern apparatus shown in FIG.36 showing the milling bit engaged with the pattern apparatus.

FIG. 38 is a perspective view of a femoral implant having a curvedimplant bearing surface.

FIG. 39 is a side plan view of the femoral implant shown in FIG. 38.

FIG. 40 is a side plan view of another embodiment of the patternapparatus and positioning apparatus of the present invention forresecting a patella.

FIG. 41 is a top plan view of the patella resection apparatus shown inFIG. 40.

FIG. 42 is a front plan view of the patella resection apparatus shown inFIG. 40.

FIG. 43 is a perspective view of another embodiment of the patternapparatus of the present invention for cutting a bone.

FIG. 44 is a perspective view of another embodiment of the alignmentapparatus shown in FIG. 24.

FIG. 45 is a partially exploded side plan view of another embodiment ofthe pattern apparatus of the present invention for cutting a bone.

FIG. 46 is a partially exploded perspective view of the interconnectionof a handle with milling bit for use in connection with pattern plateshown in FIG. 45.

FIG. 47 is front plan view of another cutting apparatus for use inconnection with the present invention.

FIG. 48 is a side plan view of the femoral implant shown in FIG. 38,FIGS. 48A, 48B, 48C and 48D being sectional views taken along lines A-A,B-B, C-C and D-D of FIG. 48, respectively.

FIG. 49 is a side plan view of the curvilinear milling bit and resectionguide shown in FIG. 35.

FIG. 50 is a side plan view of another embodiment of the femoral implantshown in FIG. 38.

FIG. 51 is an exploded view of the femoral resection alignment apparatusof the present invention showing the guide body component, a rotatingarm component, an extension rod component, and a tibial referencingcomponent.

FIG. 52 is a side plan view of the apparatus shown in FIG. 51 attachedto a flexed human knee joint including a distal femur, a resectedproximal tibia, and collateral ligaments.

FIG. 53 is a front plan view of the apparatus shown in FIG. 51 attachedto a flexed human knee joint including the distal femur, the partiallyresected proximal tibia, and the collateral ligaments.

FIG. 54 is an exaggerated front plan view of a partially resected distalfemur and a resected proximal tibia after use of the apparatus of thepresent invention shown in FIG. 51 showing placement of drill holes forattaching a cutting guide to allow for indirect control of theorientation and location of a conventional cutting guide.

FIG. 55 is a side plan view of the extension block component of thepresent invention for placement between the partially resected distalfemur and the resected proximal tibia by use of the apparatus of FIG.51.

FIG. 56 is a front plan view of the extension block shown in FIG. 55placed between the partially resected distal femur and the resectedproximal tibia by use of the apparatus of FIG. 51.

FIG. 57 is an exploded view of another embodiment of the femoralalignment apparatus of the present invention showing the guide bodycomponent, a rotating arm component, an extension rod component, and atibial referencing component.

FIG. 58 is a side plan view of the apparatus shown in FIG. 57 attachedto a flexed human knee joint including a distal femur, a partiallyresected proximal tibia and collateral ligaments.

FIG. 59 is a front plan view of the apparatus shown in FIG. 57 attachedto a flexed human knee joint including the distal femur, the partiallyresected proximal tibia, and the collateral ligaments.

FIG. 60 is a partially exploded perspective view of the apparatus shownin FIG. 57.

FIG. 61A is a perspective view of an embodiment of a femoral resectionapparatus having cutting guides, and FIG. 61B is a side view thereof.

FIG. 62A is a perspective view of the apparatus shown in FIG. 61 affixedto a femur to be resected, and FIG. 62B is a side view thereof.

FIG. 63A is perspective view of the cutting guide portion of the femoralresection apparatus shown in FIG. 61 affixed to a femur to be resected,along with a cutting tool, and FIG. 63B is a side view thereof.

FIG. 64 is a perspective view of a cutting tool and guide handle forresecting a femur.

FIG. 65A is a perspective view of the cutting tool interconnected withthe cutting guide shown in FIG. 64, and FIG. 65B is a side view thereof.

FIG. 66A is a perspective view of the positioning and drill guideapparatus of the present invention, along with a femur to be resectedhaving a intramedullary rod inserted therein, and FIG. 66B is a sideview thereof.

FIG. 67A is a perspective view of the positioning and drill guideapparatus shown in FIG. 66 positioned on a femur to be resected, andFIG. 67B is a side view thereof.

FIG. 68 is a front view of a cutting guide of the present inventionpositioned for attachment to a femur to be resected.

FIG. 69 is a front view of the cutting guide shown in FIG. 68 attachedto a femur to be resected.

FIG. 70 is a perspective view of a cutting tool and handle wherein thecutting tool has a curvilinear profile.

FIG. 71 is a side view of a cutting guide having a curved cutting pathattached to a femur to be resected.

FIG. 72 shows a number of perspective and side views of an implanthaving a curved attachment face.

FIGS. 73A and 73B show front and side views of a cutting guide forpositioning a cutting block for use with an oscillating saw forresecting a femur.

FIGS. 74A and 74B show front and side views of a distal cutting guidefor use with the cutting guide shown in FIG. 74.

FIG. 75A is a perspective view of a cutting block interconnected withthe cutting guide shown in FIG. 74, and FIGS. 75B and 75C are side andfront views thereof

FIG. 76 is a side view of the positioning and drill guide apparatusshown in FIG. 76 showing size markings thereon, and FIG. 77 is a backview thereof.

FIG. 78 is a side view of the cutting guide having a curved cutting pathshown in FIG. 71 used in connection with ligament balancing, and FIGS.79 and 80 are front and perspective views thereof.

FIGS. 81 and 82 are front and side views of a cutting guide attached toa tibia.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

As shown generally in FIGS. 1-6, the resecting apparatus of the presentinvention comprises a number of components, namely positioning apparatusgenerally indicated at 10 comprising positioning body generallyindicated at 12, angular adjustment block generally indicated at 32,rotational alignment device generally indicated at 50, pattern devicegenerally indicated at 59 and cutting means generally indicated at 90.

As shown in detail in FIG. 1, the positioning apparatus, generallyindicated at 10, includes a positioning body generally indicated at 12having sides 13, top surface 14, front surface 15, back surface 19 andcross member 18. Extending from a lower end of the positioning body 12is positioning tongue 20 having an upper surface 22. Extending into thepositioning body 12 from top surface 14 to the cross member 18 andthrough the front and back surfaces 15 and 19, is a gap generallydefined by slots 16 and partial slot walls 17. Sides 13 includeapertures 24 for receiving locking screws 25. Also extending through thebody 12 from the back surface 19 to the front surface 15 are apertures27 for receiving fixation screws 26.

The positioning apparatus 10 receives and holds angular adjustment blockgenerally indicated at 32. Angular adjustment block 32 includes a frontsurface 34 having wings 36 sized to be received by the slots 16 in thepositioning body 12 to hold the angular adjustment block 32. The angularadjustment block 32 is locked into place in the positioning body 12 bymeans of locking screws 25, which extend through apertures 24 in thepositioning body 12 and contact the wings 36 of the angular adjustmentblock 32 to secure the angular adjustment block 32 to the positioningbody 12. The angular adjustment block 32 establishes the angularalignment and anterior/posterior location of the positioning apparatus10.

The angular adjustment block 32 also includes back surface 38 and anaperture 40 extending from the back surface 38 through the angularadjustment block 32 to the front surface 34. The aperture 40 receives anintermedullary rod 42 therethrough. The intermedullary rod 42 comprisesa shaft 43 and a handle 44. The shaft 43 extends through the angularadjustment block 32 and into the intermedullary canal which extendsalong the axis of the femur to aid in establishing the orientation ofthe resection apparatus of the present invention as hereinafterdescribed.

The rotational alignment device, generally indicated at 50, includes ashaft 51 having a groove 52 therealong and a block 53 having a backsurface 54 and wings 56. The rotational alignment device 50 isinterconnected with the positioning body 12 by means of the wings 56received in slots 16 of the positioning body 12. The rotationalalignment device 50 may be secured to the positioning body 12 by meansof locking screws 25 which extend through apertures 24 in thepositioning body 12 to contact the wings 56. The locking screws 25 maybe made of various configurations depending upon their specificfunction. Importantly, the locking screws 25 are used to rigidly affixone component or device to another to ensure that the relative locationsand orientations are maintained despite the rigors of surgery.

As shown in FIG. 2, wherein the positioning body 12 is fitted with theangular adjustment block 32 and the rotational alignment device 50, theentire positioning apparatus 10 is connected to a human femur 7 by meansof the shaft 43 of the intermedullary rod 42. The shaft 43 extendsthrough the angular adjustment block 32, and thereby through thepositioning body 12 into the intermedullary canal which extends alongthe axis of the femur 7. The intermedullary rod 42, shown in FIG. 7, hasa groove 41 transversing a helical path 45 along the axis of the shaft43. The groove 41 relieves intermedullary pressure that leads to fattyembolisms. The basic concept of the intermedullary rod 42 with thegroove 41, is that as it is inserted into the femur, which containsliquid fatty tissue, the liquid fatty tissue is drawn up the groove 41of the intermedullary rod 42 to draw the fatty liquid tissue out of thefemur. Preferably, the intermedullary rod would have a hexagonal head,(not shown) to permit it to be driven by a powered device such as anelectrical hand held tool. Importantly, the groove 41 does not have acutting edge, which would risk perforation of the femoral cortex.Accordingly, the device does not cut solid material, but removes liquidmaterial from the intermedullary canal. Therefore, the risk of fattyembolism is reduced.

After positioning body 12 is properly located against the femur 7 bymeans of the intermedullary rod 42 and the angular adjustment block 32,fixation screws 26 may be advanced through the apertures 27 in thepositioning body 12 until they make contact with the distal femoralcondyles of the femur 7, and are then driven into the distal femoralcondyles of the femur 7 to initially affix the positioning apparatus tothe distal femur 7. It should be noted that the fixation screws 26 mayalso be advanced and adjusted to make up for deficiencies in the distalfemoral condyles. Accordingly, the positioning body 12 is positionedsuch that the front surface 15 is put into contact with the distalfemoral condyles by direct contact, and the tongue 20 is positionedunder the femur 7 and in contact therewith.

As can be seen in FIG. 2, the shaft 51 of the rotational alignmentdevice 50 extends above the femur 7 and allows for rotation of thepattern device 59, hereinafter described, about the distal femur 7.Additionally, the rotational alignment device 50 allows for theanterior/posterior positioning of the pattern device 59 with respect tothe femur 7. Importantly, the configurations of the positioning body 12,the angular adjustment block 32 and the rotational alignment device 50are not limited to the structure set forth herein, but may be ofdifferent shapes and may interconnect in different ways. Thesecomponents may even be formed as a unitary or partially unitary device.

As shown in FIG. 3, the pattern device 59 includes pattern plates 60having tops 61, and cutting paths, generally indicated at 62, extendingtherethrough. The cutting paths 62 outline the desired resection shapeof the distal femur 7. Generally, the cutting paths 62 could include afirst vertical path 64, extending to a first diagonal path 65, extendingto a second diagonal path 66, extending to a second vertical path 67,extending to a third diagonal path 68 and then extending to a horizontalpath 69. Alternatively, the cutting paths 62 could describe any desiredresection shape for the femur 7. The pattern plates 60 also includelocking screws 75 for interconnecting the pattern plates 60 with acrossbar 80.

The pattern device 59 of the present invention preferably includes twopattern plates 60 held in a spaced apart relationship by crossbar 80.The crossbar 80 separates the pattern plates 60 sufficiently to permitthe pattern plates 60 to extend along the sides of the distal femur 7.The crossbar 80 includes a front surface 82, back surface 84, a topsurface 83, a central aperture 86 extending from the front surface 82 tothe back surface 84, a lock aperture 88 extending through the topsurface 83, and a lock screw 89. The central aperture 86 of the crossbar80 receives the shaft 51 of the rotational alignment device 50.Accordingly, the pattern device 59 is interconnected with thepositioning apparatus 10 so that the pattern device 59 is properlyoriented with respect to the femur 7. Upon proper positioning of thecrossbar 80, with respect to the shaft 51 of the rotational alignmentdevice 50, lock screw 89 is extended through lock aperture 88 to contactthe shaft 51 to lock the crossbar 80 and, accordingly, the patterndevice 59, onto the shaft 51 of the rotational alignment device 50, andaccordingly, to positioning apparatus 10. This completed assembly isattached to the femur 7, as shown in FIG. 4.

As additionally shown in FIGS. 3 and 4, the pattern plates 60 includeplate apertures 72 for receiving cannulated screws 70 which haveapertures extending therethrough for receiving fixation nails 71therethrough. Accordingly, after the pattern device 59 is interconnectedwith the positioning apparatus 10, and properly located and orientedwith respect to the femur 7, the cannulated screws 70 are extendedthrough the plate aperture 72 to contact the sides of the distal femur7. Then, in order to fix the pattern plates 60 with respect to the femur7, the fixation nails 71 are driven into the distal femur 7 to lock thepattern plate 60 into position on the distal femur 7. The cannulatedscrews 70 have sharp leading edges for allowing decisive purchase in thedistal femur 7 before the introduction of the fixation nails 71 tocomplete fixation of the pattern device 59 to the distal femur 7.

The pattern plates 60 by virtue of the cutting paths 62, dictate theshape of the resection of the femur 7. The cutting paths 62 areessentially channels through the pattern plates 60. The cutting paths 62receive the cutting device and guide it as it resects the surface of thedistal femur 7. The pattern plates 60 straddle the distal femur 7mediolaterally and are suspended by the crossbar 80. Likewise, crossbar80 maintains the proper relationship between the pattern plates 60before and during the resection of the distal femur 7. The location ofthe crossbar 80 and accordingly, the pattern plates 60, may be adjustedwith respect to the positioning apparatus 10 by adjusting the positionof the block 53 of the rotational alignment device 50 within the slots16 of the positioning body 12, and locking the same with locking screws25.

The cutting paths 62 in the pattern plates 60 receive and guide thecutting device shown in FIG. 5 and generally indicated at 90. Thecutting device 90 performs the actual cutting of the femur 7 to resectthe femur 7. The cutting device may be of any known configuration. In apreferred embodiment, the cutting device is a drill. The drill 90 isgenerally cylindrical in shape and may possess helical cutting teethalong its length to cut the femur 7. The drill 90 includes a hexagonalend 95 to permit the use of an electric powered drive, typically anelectric drill. Further, the drill 90 includes drill bushings 92 at theends of the drill 90 to provide a non-metallic bearing between thecutting paths 62 in the pattern plates 60 to avoid galling and to ensuresmooth articulation of the drill 90 along the cutting path 62.Positioned between the drill bushings 92 and the drill 90 are retentionsprings 94 which are essentially coil springs retained within the drillbushings 92 to allow the drill bushings 92 to be easily attached andremoved from the drill 90. These retention springs 94 are commerciallyavailable in medical grade stainless steels. The drill bushings 92retain the retention springs 94 which hold the drill bushings 92 inposition 92 on the drill 90 while allowing the drill bushings 92 torotate freely. The drill 90 may also include circumferential grooves 91for allowing attachment and retention of the drill bushings 92 by meansof the retention springs 94. Importantly, the configuration of the drill90 can vary in accordance with what is known in the art, as long as thecutting device can follow the cutting paths 62 in the pattern plates 60to resect the femur 7.

As shown in FIG. 6, after the pattern device 59 is attached to thedistal femur 7, and positioned accordingly by means of the positioningapparatus 10, and secured to the distal femur 7 by means of cannulatedscrews 70 and fixation nails 71, positioning apparatus 10 may be removedfrom connection to the distal femur 7 leaving the pattern device 59attached to the distal femur 7 to permit resecting of the distal femur.The drill 90 is then positioned within the cutting paths 62 between thepattern plates 60. Next the drill 90 is rotated by power means inconnection with the hexagonal end 95, and is then moved along thecutting path 62 to resect the distal femur 7. It should also be notedthat the cutting means could be operated by hand.

Instead of two pattern plates 60, a single pattern plate could beemployed if it is sufficiently sturdy to support and guide the drill.The pattern plates 60 may also comprise plates having edges in the shapeof the desired distal femoral resection pattern. Thus, the cuttingdevice may be drawn along the edges of the pattern plates to resect thedistal femur. Further, any cutting device that can be employed to followthe cutting paths in the pattern plates is considered to be within thescope of this invention.

The resection apparatus of the present invention, through proper use aspreviously described, provides extremely accurate and reproducible bonecuts. While the anterior and distal areas of the femur will almostalways be able to be prepared in this manner, interference from softtissue such as fat and ligaments may prohibit satisfactory preparationof the posterior femur. The preparation of any remaining femoralsurfaces may be completed in any manner known in the art after using theinstrumentation of the present invention.

As shown in FIGS. 8-13, the tibial resection apparatus of the presentinvention includes a number of components, namely, cutting guide clampsgenerally indicated at 210, cutting guides generally indicated at 220,ankle clamp generally indicated at 250, alignment rod generallyindicated at 260, cutting guide clamp linkage generally indicated at270, fixation block generally indicated at 280, proximal tibialreferencing stylus generally indicated at 290, and milling bit generallyindicated at 255. It should be noted that the cutting guides 220 may beformed integrally with the cutting guide clamps 210 as shown in FIGS. 8and 9, or as separate members as shown in FIGS. 11, 12 and 13. Also, thecutting guides 220 may ride the alignment 260 as shown in FIGS. 8 and 9,or they may interconnect with the alignment rod 260 by means of cuttingguide clamp linkage 270, as shown in FIGS. 11, 12 and 13.

As shown in FIG. 8, the ankle clamp 250 is attached at or just above theankle and exterior to the skin. Any conventional ankle clamp may be usedto firmly engage the ankle, or to engage the tibia above the ankle, toobtain a reference point for the other components of the presentinvention.

The ankle clamp is interconnected with and locked into place on thealignment rod 260 in any way known in the art. Preferably, though notnecessarily, the alignment rod 260 is vertically adjustable with respectto the ankle clamp 250. This vertical adjustment can be achieved at theankle clamp 250, at the interconnection of the ankle clamp 250 and thealignment rod 260, or within the alignment rod 260 itself. As shown inFIG. 8, the alignment rod includes a first lower end 262 having anaperture 263 extending vertically therein for telescopically receiving asecond upper end 265 of the alignment rod 260. A set screw 264 isprovided for fixing the upper end 265 with respect to the lower end 262.

The fixation block 280 is interconnected with an upper end of thealignment rod 260 by means of an aperture 282 in the fixation block 280sized to receive the alignment rod 260 therethrough, or in any othermanner known in the art. A set screw 284 may be provided to extend intothe fixation block 280, through set screw aperture 286 in fixation block280, to contact the alignment rod 260, to lock the fixation block 280onto the alignment rod 260. The fixation block 280 additionally includesapertures extending vertically therethrough for receiving fixation pins288 for affixing the fixation block 280 to the proximal tibia 208.

In operation, the ankle clamp 250 is attached about the ankle, or aboutthe tibia just above the ankle, on the exterior of the skin. Thefixation block 280 is already interconnected with the alignment rod 260.It is preliminarily positioned over the proximal tibia 208, and one ofthe fixation pins 288 is driven into the proximal tibia 208. Thereafter,the alignment rod 260 is adjusted to establish proper varus/valgusalignment and flexion/extension angulation as is conventionally known.Upon proper alignment of the alignment rod 260, the other fixation pin288 is driven into the proximal tibia 208 to completely fix the fixationblock 280 to the proximal tibia 208 to lock in the proper alignment ofthe alignment rod 260. Then, the fixation block 280 may be locked intoposition on the alignment rod 260.

After properly aligning and locking in the alignment of the alignmentrod 260, the cutting guide clamps 210 and the cutting guides 220 may beemployed. The cutting guide clamps 210 are interconnected with thealignment rod 260 by means of cutting guide linkage 270. Alternatively,the cutting guide clamps 210 could directly interconnect with thealignment rod 260 through apertures in the cutting guide clamps 210, asshown in FIGS. 8 and 9. As shown in FIG. 10, the cutting guide clamplinkage 270 comprises a body 271 having an alignment rod aperture 272for receiving and riding the alignment rod 260 and a pivot locking setscrew 274 which extends into the cutting guide clamp linkage 270 throughset screw aperture 275 for contacting the alignment rod 260 and lockingthe cutting guide clamp linkage 270 with respect to the alignment rod260. It should be pointed out that it may be desirable for the alignmentrod 260 to have a flattened surface extending longitudinally along thealignment rod 260 for co-acting with set screw 274 for maintainingproper alignment between the cutting guide clamp linkage 270 and thealignment rod 260.

The cutting guide clamp linkage 270 also includes a pivot shaft 276rigidly interconnected with the body 271 of the cutting guide clamplinkage 270 by member 277 to position the pivot shaft 276 a distanceaway from the body 271 such that the cutting guide clamps 210 can beinterconnected with the pivot shaft 276 and can be properly utilizedwithout interfering with the body 271 of the cutting guide clamp linkage270.

After the alignment rod 260 is properly aligned and locked intoposition, the cutting guide clamp linkage 270 is moved into itsapproximate desired position at the proximal tibia 208. It should benoted that the cutting guide clamp linkage 270 of present invention ispositioned on the alignment rod 260 at the beginning of the procedure,prior to aligning the alignment rod 260, and prior to interconnectingthe fixation block 280 with the alignment rod 260. However, it is withinthe scope of the present invention to provide a cutting guide clamplinkage 270 which is attachable to the alignment rod 260 after thealignment rod 260 has been aligned and locked into position.

After the cutting guide clamp linkage 270 is preliminarily approximatelylocated, it is locked into place on the alignment rod 260. Thereafter,the cutting guide clamps 210 may be interconnected with the pivot shaft276 by means of corresponding pivot apertures 217 in the cutting guideclamps 210.

As shown in FIGS. 11 and 12, the cutting guide clamps 210 includeopposing hand grips 212 for grasping and manipulating the cutting guideclamps 210. Crossbar members 214 extend from the hand grips 212 to clampmembers 218. The crossbar members 214 cross over each other at crossover point 215 whereat the crossbar members 214 have mating recessedportions 216 which function to maintain the hand grips 212 in the sameplane as the clamp members 218. At the cross over point 215, thecrossbar members 214 can pivot with respect to each other such thatmovement of the hand grips 212 towards each other moves the clampmembers 218 together, and likewise, movement of the hand grip members212 away from each other serves to move the clamp members 218 apart inthe same manner as scissors or pliers. At the cross over point 215, thecrossbar members 214 have corresponding pivot apertures 217 forreceiving the pivot shaft 276 of the cutting guide clamp linkage 270.Thus, the cutting guide clamps 210 pivot about the pivot shaft 276 ofthe cutting guide clamp linkage 270. It should be noted that thecrossbar members 214 could be interconnected with each other by a rivetor other means known in the art, or could be entirely independent pieceswhich co-act as set forth above only upon being seated on pivot shaft276.

The clamp members 218 of the cutting guide clamps 210 include cuttingguide adjustment screw apertures 219 at the far ends thereof forreceiving A-P adjustment screws 230 for adjustably interconnecting thecutting guides 220 with the clamp members 218, for adjustable movementin the direction shown by arrow C in FIG. 11. The clamp members 218 maybe adjustably interconnected with the cutting guides 220 in any wayknown in the art. In one embodiment, the cutting guide adjustment screwapertures 218 are threaded and the cutting guides 220 have correspondingelongated apertures 228 extending over a portion of the length thereoffor receiving the A-P adjustment screws at a desired locationtherealong. The A-P adjustment screws include a head 231, a retaininghead 232, and a threaded shaft 234. When the cutting guides 220 arepositioned correctly with respect to the clamp members 218, the A-Padjustment screws 230 are tightened down to lock the cutting guides 220onto the clamp members 218 by actuating the head 231 to turn down thethreaded shaft 234 with respect to the clamp member 218. Note theretaining head 232 of the A-P adjustment screws prevent the shaft 234from being backed off out of engagement with the clamp member 218.

As shown in FIGS. 14 and 15, respectively, the clamp members 218 areshaped with opposing interior edges having chamfers 238 and the oppositeexterior edges of the cutting guides 220 have mating recesses 239, bothof said profiles extending along the contacting surfaces of the clampmembers 218, as seen along line A-A in FIG. 12, and the cutting guides220, as seen along line B-B in FIG. 12, to maintain a proper planaralignment therebetween. It should of course be noted that any othermethod known in the art may be employed to maintain the clamp members218 and the cutting guides 220 in alignment. Additionally, the cuttingguides 220 may include A-P adjustment screw recesses 237 for receivingthe head 231 of the A-P adjustment screw 230.

The cutting guides 220 further include tibia attachment means forattaching the cutting guides 220 to the tibia 208. Any known attachmentmeans may be employed to attach the cutting guides 220 to the tibia 208.As shown in FIGS. 9 and 11, a preferred attachment means for attachingthe cutting guides 220 to the tibia 208 are pins 236 extending throughpin apertures 227 in the cutting guides 220. The pins 236 may becaptured in the pin apertures 227, or they may be entirely separate.Preferably, means exist on the cutting guides 220 for preliminarilyattaching the cutting guides 220 to the tibia 208 prior to pinning thecutting guides 220 thereto, so that after proper positioning of thecutting guides 220, the hand grips 212 can be actuated by squeezing thehand grips 212 together to contact the cutting guides 220 against thetibia 208 so that the cutting guides 220 are preliminarily attached tothe tibia 208. Such means may include a plurality of small pins capturedby the cutting guide 220, or any other suitable means. After thepreliminary attachment of the cutting guides 220 to the tibia 208, finalattachment may be made by attachment pins 236 or by any other meansknown in the art.

The cutting guides 220, importantly, include cutting slots 222 whicheach comprise lower cutting slot guide surface 223 and upper cuttingslot retaining surface 225, as well as cutting slot entrance and exit224 at one end thereof and cutting slot end wall 226 at the other endthereof. The cutting slot 222 is of a length sufficient to extend acrossthe proximal tibia 208, at a desired angle to the intermedullary canal,at the widest point of the proximal tibia 208, to allow the entire uppersurface of the proximal tibia 208 to be cut. The cutting slot 222 is ofa size sufficient to receive a cylindrical milling bit 255 such as thatshown in FIG. 16 and described in U.S. Pat. No. 5,514,139, filed Sep. 2,1994 by Goldstein, et al. The milling bit 255 comprises central cuttingportion 257 having helical cutting teeth along its length for cuttingbone. The milling bit 255 further comprises spindles 256 extending fromthe central cutting portion 257 for supporting the central cuttingportion 257.

The milling bit 255 is inserted into and received in the cutting slot222 through cutting slot entrance 224, along the direction shown byarrow A in FIG. 16. Note that the cutting slot entrance 224 may be of awider slot area or an upturned portion of the slot 222 or the millingbit 255 may merely be inserted and removed from the slot 222 at an endthereof. The spindles 256 extend through and co-act with the lowercutting guide surface 223 and the upper retaining surface 225 of thecutting slot 222 to guide the milling bit 255 along the cutting slot 222to resect the proximal tibia 208, along the direction shown by arrow Bin FIG. 16. At an end of one or both of the spindles 256 is a means forengaging the milling bit 255 with a drive means such as an electricdrill, or other drive means. This engagement means may include ahexagonal head on one of the spindles, or any other suitable method ofengagement known in the art. Additionally, bushings may be employed,either on the milling bit 255 or captured by the cutting slot 222, toprovide a non-metallic bearing between the spindles 256 of the millingbit 255 and the cutting slot 222 to avoid galling and to ensure smootharticulation of the milling bit 255 along the cutting slots 222.Importantly, the configuration of the milling bit 255 may be varied inaccordance with what is known in the art, as long as the cutting devicecan follow the cutting path of the cutting slot to resect the proximaltibia. Additionally, it should also be pointed out that other cuttingtools may be used in accordance with the present invention, including anoscillating or reciprocating saw or other means for resecting the tibiaby following the cutting slots on the cutting guides.

After the cutting guide clamps 210 are preliminarily located along thealignment rod 260, the cutting guides 220 are adjusted with respect tothe clamp members 218 for proper anterior-posterior positioning toextend along the proximal tibia 208 for guiding the milling bit 255.Importantly, the cutting slots 222 should extend beyond the edges of theproximal tibia 208. Once proper anterior-posterior alignment isobtained, the cutting guides 220 may be locked into place on the clampmembers 218.

Thereafter, a proximal tibial referencing stylus 290 may be attached toa referencing bracket 292 on the cutting guides 220. The referencingbracket 292 may be positioned in any location on the cutting guides 220,or on any other convenient component of the tibia resection system ofthe present invention. Alternatively, the referencing stylus 290 may beformed as part of a component of the present invention, or as a separatecomponent which could function merely by contacting the cutting guides220 of the present invention or any other component thereof. Thereferencing stylus 290, shown in FIG. 13, includes stylus body 294 whichmay be interconnected with the referencing bracket 292 in any mannerknown in the art, preferably by a quick release and connect mechanism ora threaded connection. The stylus body 294 supports a stylus arm 296,which is rotatable with respect to the stylus body 294 and configured toextend out and down from the stylus body 294 to contact the proximaltibia 208 at a tip 298 of the stylus arm 296. The stylus body 294, arm296 and tip 298 are sized to contact the proximal tibia 208 to referencethe positioning of the cutting guides 220 to cut the proximal tibia at aproper distance below the proximal tibia 208 as is known in the art. Thestylus arm 296 may include more than one tip 298, such other tipsextending down from the stylus body 294 in varying distances.

In operation, one determines the desired location of the stylus tip 298,unlocks the cutting guide clamp linkage 270 to permit the linkage 270 tomove up and down the alignment rod 260, and places the tip 298 on thelowest point of the proximal tibia 208 to reference the position of thecutting guides with respect to the proximal tibia 208 and with respectto the alignment rod 260. Thereafter, the cutting guide clamp linkage270 is locked to the alignment rod 260 to lock the cutting guides 220into the proper position on the alignment rod 260, and accordingly, intoproper position with respect to the proximal tibia 208. Thereafter, thehand grips 212 are actuated to press the cutting guides 220 against theproximal tibia 208 to preliminarily lock them into position on theproximal tibia 208. Next, the cutting guides 220 are fixed to theproximal tibia 208 by pins 236 or any other desired fixation means. Thefixation block 280 can then be removed from the proximal tibia 208, andthe proximal tibia 208 may be resected.

The cutting operation is similar to the cutting operation set forth inU.S. Pat. No. 5,514,139, filed Sep. 2, 1994 by Goldstein, et al.Essentially, the cutting operation comprises inserting the milling bit255 into the cutting guide slots 222 through the slot entrance/exit 224to position the central cutting portion 257 between the cutting guides220, the spindles 256 extending through the cutting guide slots 222.After the milling bit 255 is positioned, the drive means may beinterconnected therewith, actuated, and the milling bit 255 moved alongthe cutting slots 222 to resect the proximal tibia 208.

It should be noted that a handle may be provided for attachment to thespindle which is not driven so that such spindle may be guided evenlythrough the cutting slots 222 to facilitate the cutting procedure.Alternatively, a handle can be provided which interconnects with bothspindles to further facilitate control of the milling bit 255 during thecutting procedure. Additionally, the bushings that fit over the spindles256 of milling bit 255 and ride in the cutting slots 222 may be capturedin the ends of the handle and the milling bit received therethrough.

Additionally, it should be pointed out that it is within the scope ofthe present invention to modify the cutting slots 222 such that theupper retaining surface is eliminated, and the milling bit 255 merelyfollows the lower cutting guide surface 223. With the cylindricalmilling bit 255 herein described, this is especially viable as themilling bit 255 tends to pull down into the bone as it is cutting,thereby primarily utilizing the lower cutting guide surface 223 of thecutting guide 220.

As shown in FIGS. 16-18, various other embodiments of the cutting guidesare considered within the scope of the present invention. The cuttingguide 320 shown in FIG. 16 is of a generally U-shaped configuration,having cutting guide slots 322, lower cutting guide surface 323, upperretaining surface 325, pin apertures 327 and alignment rod aperture 328.This cutting guide 320 is used in the same manner as the cutting guideshereinbefore described, the differences being that the cutting guide 320interconnects directly with the alignment rod and that various sizecutting guides must be provided to accommodate various sized tibias.

Likewise, the cutting guide 320, shown in FIG. 17, operates in the samemanner as the cutting guide devices hereinbefore described, but it doesnot include cutting guide clamps. The cutting guide 320 includes cuttingslots 322, and it interconnects directly with alignment rod by means ofaperture 328. The distance between facing members 330 can be adjusted bymoving base members 332 and 334 with respect to each other to size thecutting guide 320 for the tibia to be cut. Upon proper sizing, the basemembers 332 and 334 may be locked with respect to each other by setscrew 336 or any other means known in the art.

FIG. 18 shows an embodiment of the cutting guide for use when thepatellar tendon, the patella, or the quad tendon interferes with theplacement of the other cutting guides of the present invention. As shownin FIG. 18, the cutting guide 350 may be directly interconnected withthe alignment rod, and positioned on the tibia as hereinbefore setforth. Basically, this embodiment of the invention includes only onecutting guide. The cutting guide 350 and the cutting guide slot 322 maybe wider than in the previous embodiments to help stabilize the millingbit in operation. In this embodiment, the milling bit may be firstplunged across the tibia, and then moved therealong. The milling bit maybe spring loaded to increase resistance as it is plunged through thecutting guide to bias the bit against being plunged too far across thetibia to cause damage to the tissue about the tibia. Additionally, asupport member, not shown, could be provided to extend from the cuttingguide 350, over and across the tibia to the other side thereof where itcould have a slot to capture the milling bit and provide additionalsupport thereto. The reference numerals 338, 360 and 392 correspond tothe reference numerals 238, 260 and 292 respectively.

As shown generally in FIGS. 19-23, the pattern apparatus of the presentinvention, generally indicated at 430, comprises pattern plates,generally indicated at 432, and crossbar apparatus, generally indicatedat 440.

Pattern Plates

Pattern plates 432 include fixation apertures 434 extending therethroughfor accepting fixation means, as will hereinafter be described, foraffixing the pattern plates 432 to a bone. The pattern plates 432further include a cutting path 436 for dictating the path along which abone is to be cut. As shown in FIGS. 19-23, which are directed to anembodiment of the present invention for resecting a distal femur, thecutting path 436 in the pattern plates 432 matches the profile of afemoral component of a knee prosthesis for resecting the femur to acceptthe femoral component of the prosthesis. Importantly, as willhereinafter be described, the cutting path 436 could be identical insize and shape to an interior bearing surface of a femoral component ofthe knee prosthesis, or could vary in size and shape in accordance withalternative methods and apparatus used to perform the resection. Forexample, the cutting path could be larger than the desired resection,but a larger cutting tool could be used to arrive at a resection of thedesired the desired size.

In the embodiment of the present invention shown in FIG. 21, the cuttingpath 436 includes an anterior end 436A, an anterior cut portion 436B, ananterior chamfer portion 436C, a distal cut portion 436D, a posteriorchamfer portion 436E, a posterior cut portion 436F, and a posterior end436G. Alternatively, the cutting path 436 could be of any desired shapein accordance with the prosthesis systems of the various manufacturersof such prosthesis, the desires of the surgeon utilizing the apparatusand/or the application for which a bone is to be cut.

Although a single pattern plate 432 may be employed in resecting a femuror other bone (and in some cases, i.e., a partial femur resection, itmay be preferable to employ a single pattern plate 432), two patternplates 432 are generally employed to co-act with each other to support acutting means on two sides of a bone to be cut. In the case of resectinga femur, a preferred embodiment of the present invention, as shown inFIGS. 19-21, comprises two pattern plates 432 positioned on opposingsides of a femur. The pattern plates 432 are interconnected with eachother, and maintained in proper alignment with respect to each other bya crossbar apparatus generally indicated at 440, to straddle a bone. Thepattern plates 432 include crossbar apertures 438 for interconnectingwith the crossbar apparatus 440. The pattern plates may also includecrossbar slots 439 for permitting quick connect/disconnect between thepattern plates 432 and the crossbar apparatus 440. Of course, it shouldbe noted that the pattern plates 432 could interconnect with thecrossbar in any other manner known in the art, or especially with bonecutting applications other than resecting the femur, the pattern plates432 could be used without a crossbar.

Crossbar Apparatus

The crossbar apparatus 440 includes a number of component parts, namely,T-bar 442 having a top 444 and a stem 446 interconnected with andextending from the top 444 in the same plane. The T-bar 442, shown inthe figures, comprises a flat metal member having a uniform rectangularcross-section through both the top 444 and the stem 446. Three threadedlock apertures 448 are formed through the T-bar 442, one at each end ofthe top 444 and at the far end of the stem 446. Lock screws 450; havinggripable heads 452 and shafts 454 with threaded waists 456, threadablyengage the threaded lock apertures 448 in the T-bar 442. The lock screws450 further include pin holes 458 extending radially through the shafts454 at the terminal ends thereof for receiving pins 459 for capturingthe lock screws 450 on the T-bar 442.

The crossbar apparatus 440 further includes linkages 460 having a firstend for interconnection with the T-bar 442 and a second end forsupporting and engaging pattern plates 432. The first ends of thelinkage 460 include a lower flat surface 462 for contacting the T-bar442, overhanging shoulders 464 for contacting the sides of the T-bar442, and an upper flat surface 466 for contact with the lock screws 450for locking the linkages 460 onto the T-bar 442. As shown in detail inFIG. 23, the second ends of the linkage 460 include cylindrical supports468 for supporting the pattern plates 432 thereon. The cylindricalsupports 468 include axial extending apertures 469 for receiving capturepins 470 therethrough, the capture pins 470 including flanged ends 472and threaded ends 474. The capture pins 470 serve to capture patternlock nuts 476 on the linkages 460, the capture pins 470 extendingthrough the axial apertures 469, the flanged ends 472 retaining thecapture pins 470 therein, the threaded ends 474 extending out of thecylindrical supports 469 and into the threaded interior 477 of thepattern lock nuts 476. The cylindrical supports 468 receive the crossbarapertures 438 of the pattern plates 432 and the pattern lock nuts 476are threaded down onto the capture pins 470 to secure the pattern plates432 to the crossbar apparatus 440. Of course, other embodiments of thecrossbar apparatus sufficient for supporting the pattern plates of thepresent invention are considered within the scope of the presentinvention.

Positioning Apparatus

As shown in FIGS. 24-28, the positioning apparatus of the presentinvention is generally indicated at 510. The positioning apparatusgenerally comprises positioning body 520 and alignment apparatus 580.The positioning body 520 comprises a frame 522 having sides 524, bottom526 and top 528 arranged to form a frame having a rectangular aperturedefined therewithin. The top 528 further includes a head 530 formedthereon having a linkage aperture 532 extending therethrough at an upperend thereof, and having a lock aperture 534 extending from the upperedge of the head to the linkage aperture 532. A lock screw 536 having athreaded shaft 538 extends into and is threadably engaged with the lockaperture 534 for locking the head 530 to a linkage, namely crossbarlinkage 540. Crossbar linkage 540 includes a first end having an upperflat surface 542 for interconnecting with the crossbar in a mannersimilar to the pattern plate linkages for attaching the pattern platesto the crossbar as hereinbefore described. The crossbar linkage 540further includes a shaft 544 which is received by the linkage aperture532 in the head 530 to interconnect the positioning body 520 with thecrossbar linkage 540 and hence with the crossbar apparatus 440 and thepattern apparatus 430. The positioning body can then be locked onto thecrossbar linkage 540 by means of lock screw 536.

The end of shaft 544 of the crossbar linkage 540 includes projections546 extending axially from the shaft 544. When the shaft 544 ispositioned in the linkage aperture 532, the projections 546 extendbeyond the frame 522 and are received in slots 556 in alignmentindicator 550 for keying the orientation of the alignment indicator 550with the alignment of the crossbar linkage 540, and hence with thealignment of the crossbar apparatus 440 and the pattern apparatus 430.The alignment indicator 550 includes an alignment arrow 552 forindicating alignment on a scale that may be set forth on the positioningbody 520. An indicator pin 558 having a shaft 559 may be employed to pinthe alignment indicator 550 to the crossbar linkage 540.

Attachable to the bottom 526 of the positioning body 520 is skid 560.The skid 560 includes skid apertures 562, one of which may include anaperture flat 564 for ensuring proper alignment and positioning of theskid 560 with respect to the positioning body 520. The skid 560 isattached to the bottom 526 of the positioning body 520 by means of skidbolts 566 having threaded shafts 568 which co-act with threadedapertures in the bottom 526 of the positioning body 520. Of course, theskids could be formed integrally as part of the positioning body.

The sides 524 of the positioning body 520 include slots 570 extending ina facing relationship along the sides 524. The slots extend fromexterior surfaces of the sides to interior surfaces thereof, i.e., tothe interior rectangular aperture formed within the positioning body520.

Alignment Apparatus

The alignment apparatus 580 interconnects with the positioning body 520by means of alignment guide body 582 which is a U-shaped member havingsides 584 and a bottom 586. The alignment guide body 582 is sized to fitwithin the rectangular aperture formed within the positioning body 520.The alignment guide body 582 is retained within the positioning body bymeans of guide studs 572 that extend through the sides 524 of thepositioning body 520 within the slots 570 and into guide apertures 588at one side of the alignment guide body 582. At the other side of thealignment guide body 582 a lock stud 584 extends through the slot 570 inthe side 524 of the positioning body 520 and into a threaded lockaperture 589 in the alignment guide body 582. The guide studs 572 andthe lock stud 574 co-act to maintain the alignment guide body 582 withinthe positioning body 520, and the lock stud 574 can be threaded down tolock the vertical position of the alignment guide body 582 with respectto the positioning body 520.

At upper ends 590 of the sides 584 of the alignment guide body 582 areplate apertures 591. The alignment plate 592 includes bolt apertures 595aligned with the plate apertures 591 of the alignment guide body 582,and plate bolts 594 extend through the bolt apertures 595 in thealignment plate 592 and into the plate apertures 591 to secure thealignment plate 592 to the alignment guide body 582. The alignment plate592 further includes rod guide aperture 597 which receives rod guidebolt 596 therethrough to interconnect the alignment plate 592 with theIM rod guide 610 as will hereinafter be described. Additionally, thealignment plate 592 includes lock slot 606 extending through thealignment plate 592 along an arc for purposes hereinafter described.

The IM rod guide 610 includes IM rod aperture 612 for receiving an IMrod therethrough. The IM rod guide 610 is interconnected at a forwardend with the alignment plate 592 by means of plate attachment aperture614 on the rod guide 610 which receives rod guide bolt 596 therein,after such bolt 596 passes through the alignment plate 592 to secure therod guide 610 in a pivoting relationship with respect the alignmentplate 592 at forward ends of the rod guide 610 and the alignment plate592. The IM rod guide 610 is additionally interconnected with thealignment plate 592 by rod guide lock bolt 600 which includes a threadedshaft 210 and pin aperture 602. The rod guide lock bolt 600 extendsthrough the slot 606 in the alignment plate 592 and through threadedlock bolt aperture 616 in the rod guide 610 where it is captured bymeans of capture pin 618 extending through the pin aperture 602. The IMrod guide further includes rod guide handle 620 which is configured tobe easily manipulated.

The alignment plate 592 further includes a printed angular rotationscale which indicates the degree of angular rotation between the rodguide 620 and the alignment apparatus, and hence, the angular rotationbetween the IM rod and the positioning body 520. After such alignment isdetermined, it can be locked into place by tightening down rod guidelock bolt 600. Thereafter, with such angular rotation fixed, the patternapparatus 430 can be positioned with respect to the bone to cut, and thepositioning apparatus 510 can be removed from interconnection with theIM rod and the pattern apparatus 430, the IM rod removed from the bone,and bone cutting can be initiated.

In another embodiment, as shown in FIGS. 28A, 28B, 28C and 28D, IM rodguide block 630 is used instead of the alignment plate 592 and thealignment guide body 582. The IM rod guide block 630 includes a rearsurface 632, a front surface 634, a top surface 636 and sides 638. Thesides 638 include retaining flanges 640 at the rear and front surfacesfor retaining the IM rod guide block 630 within the rectangular apertureformed by the positioning body 520. The IM rod guide block 630 furtherincludes IM rod aperture 642 extending through the block 630 from therear surface 632 to the front surface 634 for accepting the IM rodtherethrough. The rod aperture 642 extends through the guide block 630at an angle A with respect to axis of the guide block for accommodatingthe varus/valgus orientation of the femur. The guide block 630 is partof a set of blocks having rod apertures of various angles extendingtherethrough, i.e., 5, 7, 9, 11, 13 degrees, for use with femurs havingvarying angles of orientation. The guide block 630 also includes lockaperture 646 for locking the proper vertical position of the guide block630 with respect to the positioning body 620. The guide block 630 mayadditionally include two apertures 644 for accepting an anteriorreferencing arm for use in determining the anterior/posterior size ofthe femur. It should be noted that other alignment means for aligningthe positioning apparatus with respect to a bone to be cut areconsidered within the scope of the present invention.

Fixation Means

Various fixation means, including those known in the art, can be used tofix the pattern plate or plates to the femur or other bone to be cut.FIG. 29 shows a preferred fixation means, generally indicated at 660.The fixation means 660 includes a spike plate 664 carrying on one sidethereof a spike or spikes 662 for contacting, and even extending into,bone 661. At the other side of the spike plate 664 is spike plate socket666 for receiving plate driving ball 668 in a keyed relationshiptherewith. The driving ball 668 is interconnected to an end of drivingsleeve 670 and which has a threaded aperture extending therein from theopposite end thereof.

A driving screw 672 having a threaded shaft 674 co-acts with theinternally threaded driving sleeve 670 such that the rotation of thedriving screw 672 either propels or retracts the driving sleeve 670, aswell as the spike or spikes 662, with respect to the driving screw 672.The driving screw 672 further includes a captured head 678 and captureflange 676. The captured head 678 is received within a fixation aperture434 in the pattern plate 432, the capture flange 676 preventing thecaptured head 678 from passing through the fixation aperture 434. Adriving cap 680 is interconnected with the captured head 678 at theoutside of the pattern plate 432. The driving cap 680 includes a shaft682 received by the captured head 678, a flanged head 684 for contactingagainst the outside of the pattern plate 432, and a driver recess 686 ofany desirable configuration for receiving driving means such as a flat,phillips or hex head driving means for driving the driving cap 680 todrive the driving screw 672 to move the spike or spikes 662 towards oraway from a bone.

Importantly, this type of fixation means allows for fixation of thepattern plates 432 to even osteoporotic bones. Additionally, thisfixation means is self-adjusting to fit changing contours of bones.Further, because of its relatively low profile, this fixation means doesnot interfere with soft tissue about a bone to be cut. Other types offixation means include cannulated screws, pins, spring loaded screws,captured screws, spiked screws and/or combinations thereof, all of whichare considered within the scope of the present invention and could beused in connection with the present invention.

Anterior/Posterior Referencing

The apparatus of the present invention further includes built-inanterior/posterior referencing means as shown in FIG. 30 for use inconnection with preparation of the distal femur in total kneereplacement. As is known in the art, anterior/posterior referencingrefers to proper positioning of the distal femur cuts with respect tothe anterior and/or posterior sides of the femur or other bone to becut.

The anterior/posterior difference between femoral implant sizes may varyby as much as 3 to 5 millimeters between sizes. Of course, many femursare between sizes. Disregarding proper positioning of the cutting guideand the associated femur cuts could lead to flexion contracture (wherethe bone is slightly below size and the implant adds too much materialto posterior side of femur which results in the inability to move theknee into flexion because the extra posterior material contacts thetibial implant components) and/or anterior notching of the femur (wherethe bone is slightly above size and the anterior runout point of theanterior cut is recessed in the anterior side of the bone in a sharpnotch, thus seriously weakening the structural integrity of the distalfemur, especially under cyclic fatigue or impact loading conditions).

Anterior referencing systems have a major advantage over posteriorreferencing systems in that they theoretically never notch the anteriorcortex of the femur. The drawback of anterior referencing is that aslightly larger bone results in collateral ligament laxity in flexionand a slightly smaller bone will result in collateral ligamenttightening in flexion (flexion contracture).

Posterior referencing systems have a major advantage over anteriorreferencing systems in that they theoretically never develop flexioncontracture. The drawback is that a slightly large femur is prone toanterior notching, which can increase the likelihood of distal femoralfractures under either impact loading or cyclic fatigue loading.

Another approach to anterior/posterior referencing is a hybrid designthat allows for both anterior and posterior referencing. The positioningapparatus 510 references the posterior femoral condyles (posteriorreferencing), while the pattern plates 432 allow for precise referencingof the anterior femoral cortex. The anterior referencing device can beas simple as that shown in FIG. 30, wherein a referencing pin 694 isplaced through the anterior-most cutting paths 436 of the pattern plates432 to contact the anterior femoral cortex 661. The pattern plates 432include markings S (smaller size) and L (larger size). When the pin 694falls between the S and L marks, the pattern plates 432 are the propersize and are properly positioned for that femur. If the pin 694 fallsoutside the range marked by S and L towards the S side, a smaller sizepattern plate should be used, and conversely, if the pin 694 fallsoutside the range on the L side, a larger size pattern plate should beused. Alternatively, the pattern plate 432 could be adjusted verticallyvia means not shown to compensate for between-size bones.

In another embodiment, the pattern plate could include a plungerassembly at the anterior end of the cutting path. The plunger could bemovable vertically to contact the femur and indicate size of the femurwith respect to the pattern plate in use. As such, the plunger could beincrementally marked from +4 to −4 millimeters with 0 being the propersize for the pattern plates in use. Again, the pattern plates could besized up or down if the femur is off of the scale, or the pattern platescould be moved up or down to compensate for between size bones dependingupon surgeon preference. If, for example, a bone registers a +2,anterior notching of the femur would occur. To avoid this, the patternplates could be moved anteriorally 1 millimeter to +1. In this manner,anterior notching would be minimized and the posterior femoral condyleswould only lack 1 millimeter of material, which should not bedetrimental as some ligamentous laxity in flexion is acceptable becausethe collateral ligaments are normally slightly looser in flexion thanthey are in extension. It should be noted that the radii or curve in theanterior-most area of the cutting path will assure that anteriornotching is easily avoidable.

Pattern Plate with Tracking Means

Another embodiment of the pattern plates of the present invention isshown in FIG. 31. In this embodiment, the pattern plates, generallyindicated at 710, basically comprise only the lower edge, or bearingsurface 716 of the cutting path 436 of pattern plates 432 shown in FIGS.19-21. Accordingly, the pattern plate 710 includes fixation apertures712 and crossbar aperture 714. The milling apparatus bears against thebearing surface and follows the same therealong to resect the bone inaccordance with the shape of the bearing surface 716. Of course, thebearing surface could be smaller or larger than the desired cut locationdepending on the size of the milling apparatus. The pattern plate 710could further include a groove or guide means 718 extending in thepattern plate alongside the bearing surface and the milling apparatuscould include an arm or other retaining linkage 717 extending from thehandle or bushing of the milling apparatus and into the groove 718 forengagement with the groove 718 for guiding or retaining the millingapparatus along the bearing surface 716 of the pattern plate 710.Alternatively, it should be noted that the bearing surface could alsocomprise just the upper surface of the cutting path 436 of the patternplates 432, as shown in FIGS. 19-21.

Ligament Balancing

As shown in FIG. 32, an alternative embodiment of the alignment guidebody 730 can be used for performing ligament balancing. The alignmentguide body 730 of this embodiment can include a skid 732 formed as apart of the guide body 730, or attachable thereto. The skid 732 is of arelatively thick cross-section, approaching or equal to thecross-section of the guide body 730. The guide body 730 is attached tothe femur 661 and the femur may be moved from extension to flexion andback, while the ligament tension of the collateral ligaments isreviewed. Ligamentous release can be performed to balance the ligaments.Further, shims 736, in either a rectangular cross-section (FIG. 32A) oran angled cross-section (FIG. 32B), can be used in connection with thealignment guide body 830 and skid 732. These shims could be positionedbetween the underside of the skid 732 and the resected tibia.

Milling Means

In a preferred embodiment of the invention, a cylindrical milling bit isused for following the cutting path described in the pattern plates forresecting a bone. Importantly, it is within the scope of the presentinvention to use a flat reciprocating bit, much like a hacksaw, forfollowing the cutting paths described in the pattern plates forresecting a bone.

Further, it may be desirable to make all or some of the cuts using acylindrical milling bit or a flat reciprocating bit having a smoothcenter section without cutting means. An advantage of a cutting toolwithout cutting means along a center portion thereof is the protectionof posterior cruciate ligament during resection of the femur.Accordingly, one cutting tool could be used to make the anterior cut,the anterior chamfer, the distal cut and the posterior chamfer, whileanother cutting tool, with a smooth center portion, could be used tomake the posterior cut to avoid any chance of jeopardizing the posteriorcruciate ligament.

Additionally, the milling bits herein described can be used with orwithout a guide handle as will hereinafter be described. Further, itshould be pointed out that it is within the scope of the presentinvention to fabricate the milling bit or other cutting tool from metalas heretofore known, or to alternatively fabricate the milling bit orother cutting tool from a ceramic material. An advantage of a ceramicmilling bit or cutting tool is that such resists wear and, accordinglywould be a non-disposable component of the present invention which wouldhelp to reduce the cost of the system of the present invention.

Three Dimensional Shaping

Initially, it should be noted that the term cutting profile the profilegeometry of a mediolateral section taken normal to the cutting paththrough the bony surfaces created by cutting the bone. As shown in FIG.33, in an alternate embodiment of the present invention, a millingapparatus having a three-dimensional profile, or a form cutter, can beused to shape a bone in three-dimensions. The curved profile milling bit750, like the milling bits used in the previous embodiments of thepresent invention, includes cutting teeth 752 along the length thereofand spindles 754 at the ends thereof. This milling bit 730 can follow apattern described by pattern plates and can be guided with a handle aswill be hereinafter described.

Importantly, by using a milling bit having a curved profile, one can cuta femur to resemble the natural shape of the femur, i.e., the resectedfemur would include condylar bulges and a central notch. This wouldreduce the amount of bony material that must be removed from the femurwhile maintaining the structural integrity of the femur. Of course, anyprosthetic implant used for attachment to a femur resected by the curvedprofile milling bit would necessarily have an appropriately contouredinner fixation surface for mating with contoured surface of the femur.Additionally, it should be noted that the curved profile milling bitcould have one or more curvilinear bulges along the length thereof, asshown in FIG. 33, or alternatively, could have one or more bulgesdiscretely formed along the length thereof as shown in FIG. 35.

Guide Handle

As shown in FIG. 34, a guide handle, generally indicated at 698 may beused to guide the milling bit along the cutting path of the patternplate. The guide handle 698 comprises a grip portion 700 which isgrasped by the user for manipulating the guide handle 698 andaccordingly, the milling bit. The grip portion 700 is interconnectedwith a crossbar member 702 which includes a extension member 703telescopically interconnected therewith. The crossbar member 702 and theextension member 703 may be positioned perpendicular with respect togrip portion 700. The extension member 703 is telescopically movable inand out of crossbar member 702. Means may be provided for locking therelative position of the extension with respect to the crossbar. Also,it should be noted that the grip portion may rigidly or pivotally beinterconnected with the crossbar as desired.

Extending from outer ends of the crossbar 702 and the extension member703 are sidebars 704 in facing and parallel relationship. The sidebars704 have two ends, the first of which are interconnected with thecrossbar and the extension member, and the second of which areconfigured to receive and capture spindles or bushings of a milling bitin spindle bushings 706. The spindle bushings are positioned in a facingrelation and could include captured bushings. The captured bushingsreceive the spindles of a milling bit. The captured bushings are sizedto be received by the cutting path in the pattern plates and co-acttherewith to guide a milling bit therealong. Accordingly; after thepattern plate or plates are attached to a bone, the milling bit isplaced into the cutting path. Next a milling handle 698 is positionedsuch the spindle bushings are aligned with the spindles of the millingbit. Next, the extension is actuated to retract into the crossbar tomove the spindle bushings onto the spindles of the milling bit wherethey are captured. Next, the spindle bushings are positioned within thecutting path of a pattern plate or plates. If necessary, the extensionand crossbar can be locked down to lock the entire apparatus. Next, themilling bit is actuated and the grip portion of the handle is graspedand manipulated to move the milling bit along the cutting path to cut abone.

Distally Positioned Pattern Plate

As shown in FIGS. 35-37, in an alternate embodiment of the presentinvention for resecting a femur, the plates could take the form of arail assembly, generally indicated at 760, positioned distally of thedistal femur 661. The plates could be affixed to the femur by fixationarms 762, attached at one or more points to the rail assembly 760, andincluding fixation apertures 764 for receiving fixation screws or otherfixation means for attaching the fixation arms 762, and hence the railassembly 760, to a distal femur 661. The rail assembly 760 includes oneor more guide rails 766 which match the shape of the desired resection,though the rails may be larger or smaller depending on the dimensions ofthe milling apparatus used and the positioning of the assembly 760 withrespect to the femur. In the case that the assembly 760 includes twoguide rails 766, as shown, an end rail 768 may be used to interconnectsuch guide rails 766. The end rail 768 could be replaced by a connectionmeans similar to the crossbar apparatus 440, hereinbefore described. Therail assembly may be positioned on the distal femur in accordance withthe teachings contained herein, or in any other manner known in the art.After alignment, according to any means disclosed herein or known ordeveloped, and after fixation of the assembly to a femur, a milling bit770 may be used to follow the guide rails 766 to resect the femur 661,the guide spindles 772, or bushings (not shown), of the milling bit 770,contacting and riding the guide rails 766. Importantly, the railassembly 760 is attached to a femur and used in much the same way as thepattern plates previously described with the exception that the railassembly can be positioned substantially distal of the femur, therebypotentially requiring less exposure and possibly resulting in lessinterference for placement thereof. The rail assembly 760 could furtherinclude an upper retaining rail for forming a slot or cutting path forcapturing the milling bit therein. Additionally, it should be noted thatany milling bit described herein could be used with rail assembly 760including a curved profile milling bit.

Curvilinear Implants

As shown in FIGS. 38 and 39, an implant 780 may have curvilinearinterior surfaces 782, as well as a more conventional curvilinearexterior surface. The particular example cited herein is a femoralimplant used in total knee arthroplasty but the principles describedherein may be applied to any application where foreign or indigenousmaterial is affixed to an anatomic feature. The curvilinear bonesurfaces necessary for proper fixation of such an implant may begenerated through the use of the curvilinear milling or form cutter andthe curvilinear cutting path means discussed herein. While it ispossible to use multiple form cutters with differing geometries and,therefore, an implant with an internal geometry that varies along thecutting path from the anterior to the posterior of a femur, for the sakeof intraoperative time savings a single form cutter is preferable.

The mediolateral cross-sectional internal geometry of such an implant,and therefore the necessary resected bony surfaces of the femur, areconsistent about the cutting path in a single form cutter system. Itshould be noted that the implant may possess a notch between members 784(posterior femoral implant condyles) in the areas approximately inbetween the distal and posterior femoral condylar areas to accommodatethe posterior cruciate ligament and other factors. Because of the notchbetween the posterior femoral condyles it may not be necessary for theform cutter to cut any material in the notch. It may be desirable toprovide outer flat surfaces 785 with an adjoining curvilinear surface782 positioned therebetween. Other combinations of flat or curvilinearsurfaces are also within the scope of the present invention.

Additionally, it may be advantageous to utilize a secondary form cutteras shown in FIG. 47 for use in creating a slot or slots in or near thedistal area of the femur after it has been resected. Such a secondarycutter 790 would include engagement means 792 for engagement withdriving means, and a shaft 794 carrying cutters 796 for cutting slotsinto the femur through one or more of the resected surfaces thereof.Through the inclusion of an additional or adjunct cutting path in thepattern means, it would be advantageous to utilize the form cutter tocreate the aforementioned slots to accommodate the fixation fins whichmay be molded as an integral part of the interior surface of theimplant. These fins would provide mediolateral fixation stability inaddition to that provided by the trochlear groove geometry of theimplant. Further, the fins also provide for additional surface area forbony contact and ingrowth to increase implant fixation both in cementedand cementless total knee arthroplasty.

There are numerous advantages to the femoral component herein described.Foremost, it will allow for the thinnest implant cross-section possible(perhaps 3 mm to 6 mm in thickness) and therefore necessitate theremoval of the least amount of viable osseous tissue. This is especiallycritical in situations where the probability of revision surgery is highand the amount of viable bone available for revision implant fixationand apposition is a significant factor in the viability of the revisionprocedure. Since the form cutter configuration allows for similaramounts of tissue to be removed from the trochlear groove, the bonyprominences surrounding the trochlear groove, the femoral condyles, andthe other articular surfaces of the femur, the external geometry of thefemoral implant can be optimized for patellofemoral articulation as wellas tibiofemoral articulation. In essence, the kinematics of theartificial joint could be made to be as close as possible to that of ahealthy, natural knee joint. In addition, the curvilinear geometry ofthe implant dramatically decreases the stress risers inherent inconventional rectilinear femoral implants and allows for a thinnercross-sectional geometry while potentially increasing the resistance ofthe implant to mechanical failure under fatigue or impact loading.Conversely, the curvilinear geometry of the implant may also allow foran advantageous reduction in the flexural rigidity of the implant whichmay result in avoidance of the “stress-shielding” inherent in rigidimplant designs. Stress shielding being a phenomenon that may occur whenliving bony tissue is prevented from experiencing the stresses necessaryto stimulate its growth by the presence of a stiff implant. Thisphenomenon is analogous to the atrophy of muscle tissue when the muscleis not used, i.e., when a cast is placed on a person's arm the musclesin that arm gradually weaken for lack of use.

Additionally, the curvilinear implant design may allow for the use of aceramic material in its construction. Since ceramics are generallyrelatively weak in tension, existing ceramic implant designs containvery thick cross-sections which require a great deal of bony materialremoval to allow for proper implantation. Utilization of ceramics in thecurvilinear implant will not only allow for the superior surfaceproperties of ceramic, but also avoid the excessively thickcross-sections currently required for the use of the material.

This could result in a less expensive femoral implant because of thereduced amount of material needed for the implant, as well as animproved, more natural, and even stronger knee replacement. It may bedesirable to vary the cross-section of the implant 780 to assist inseating the implant and to increase the strength and fit of the implant.The implants of the present invention having curvilinear implantsurfaces could be fabricated of metal, plastic, or ceramic or any othermaterial. Further, the thickness of the implants and the materialrequired to fabricate the implant could be reduced as the implants areadapted to increasingly curvilinear surfaces. Also, it should be pointedout the such implants with curvilinear implant surfaces require lessbone to be removed to obtain a fit between the implant and the bone.Finally, it should be noted that curvilinear milling bits hereinbeforedescribed would work well for preparing a bone to receive an implantwith curvilinear interior implant surface.

Patella Shaping

The apparatus for preparing a patella, as shown in FIGS. 40-42,comprises a plier-like patella resection apparatus generally indicatedat 800. The patella resection apparatus 800 includes grip handles 802for manipulating the apparatus, cross-over members 804 pivotallyinterconnected with each other by pin 806, and patella clamp members 808extending from the cross-over members in parallel and facing relation.The patella clamp members 808 have beveled edges 810 for contacting andsupporting a patella along the outer edges thereof Guide memberstructures 812 are mounted on each of the patella clamp members 808 toform a retainer for a cutting means to follow a cutting path defined bythe upper surface of the clamp members. Bushings 814 are captured withinthe retainer and the cutting path for receiving a cutting means 816 andguiding the cutting means 816 along the cutting path.

In preparing the patella, the pattern device may be an integral part ofthe positioning apparatus which is oriented and located by referencingthe geometry of the patella itself as well as the structures of thepatellofemoral mechanism to determine the location and orientation of apredominantly planar resection. The cutting device may then be employedto perform the resection of the patella by traversing the path dictatedby the pattern device, thus dictating the final location and orientationof the patella prosthesis.

Bone Substitution and Shaping

Referring now to FIG. 43, another embodiment of the pattern apparatus ofthe present invention for cutting bone is shown. This embodiment of theinvention includes pattern plates 832 having cutting paths 836 describedtherein. The pattern plates 832 may be positioned on a bone 828 having atumor or other pathology 829 associated therewith. The pattern plates832 may be interconnected by crossbars 838 with opposing pattern plates(not shown) positioned on the opposite side of the bone 828. Further,each set of pattern plates 832 could be interconnected by means ofpositioning rod 839 extending between the crossbars 838 to maintain therelative location and orientation between the sets of pattern plates832. The pattern plates can be positioned along the bone in accordancewith what is known in the art, disclosed herein or hereafter developed.After the pattern plates are properly positioned, they can be affixed tothe bone 828 with fixation means extending through fixation apertures834. After the pattern plates are properly located and affixed to thebone, cutting can commence by traversing a cutting means along thecutting paths 836 of the pattern plates 832. By this step, the tumor orother pathology 829 can be cut from the bone 828 and a bone graft orother surgical procedure can be implemented to repair and/or replace thebone that has been cut. The benefits of cutting a bone with the patternplates of the present invention include providing smooth and even cutsto the bone to facilitate fixation of bone grafts or other means forrepairing and/or replacing bone. Further, the same pattern plates can beused to cut another identical sized and shaped bone for grafting to thefirst bone to replace the cut away bone.

Alternate Positioning and Alignment Guide

An alternate positioning and alignment guide is generally indicated at840 in FIG. 44. The positioning body 840 comprises a crossbar linkage842 and an alignment indicator 844 at an upper end thereof forinterconnecting with a crossbar to align pattern plates interconnectedwith such crossbar. The positioning body 840 also includes an alignmentblock 846 for interconnecting with an intramedullary rod in much thesame manner as the IM rod guide block shown in FIG. 28. The alignmentblock 846 is vertically movable along the positioning body 840 and canbe locked into a desired position by means of lock screw 860 which bearsagainst a flange 848 of the alignment block 846. The positioning body840 further includes skids 850 for contacting the posterior surface ofthe distal femoral condyles for referencing same.

Unicondylar and/or Single Pattern Plate Support

As shown in FIGS. 45 and 46, one pattern plate of the present inventioncan be used by itself to guide a cutting means along a cutting path tocut a bone. Such an application is particularly useful for unicondylarresecting of a femur. Use of a single pattern plate 862 is facilitatedby bushing 868 having an outer flange 870 with a bearing surface 872 andan internal bore 874 sized to receive a spindle 865 of a cutting tooltherein. The bushing 868 is sized to fit into the cutting path 864 ofthe pattern plate 862, the bearing surface 872 of the flange 870contacting the side of the pattern plate 862. Washer 876 includes acentral bore 878 sized to receive the far end of the bushing 868extending past the pattern plate 862, the washer bearing against theside of the pattern plate 862 opposite the side that the bearing surface872 of the flange 870 of the bushing 868 bears against. Thus, the washerand the bushing co-act to form a stable link with a pattern plate. Asshown in FIG. 46, this link can be fortified by means of bearing arms880 interconnected with the bushing and the washer, or formed integrallyas part thereof, which by pressure means are forced together to retainthe bushing within the cutting path of the pattern plate. After thebushing is captured within the cutting path, the spindle of the cuttingmeans can be inserted through the bushing and interconnected with means866 for driving the cutting means. Alternatively, it should be pointedout that when using a single pattern plate to cut a bone, it may bedesirable to support the cutting means at the pattern plate and also atthe other end thereof. One could effect such desired support at theother end of the cutting means by a brace or other linkageinterconnecting the other end of the cutting means with a secondarysupport or anchor means positioned on the opposite side of the bone orat another location.

Revisions

Conventional revisions require removal of the old implant and thereferencing of uncertain landmarks. Revisions, by means of the presentinvention, allow for reference of the implant while it is still on thebone. One can obtain varus/valgus referencing, distal resection depth,posterior resection depth and rotational alignment by referencing thegeometry of the implant with the alignment guide. An extramedullaryalignment rod can be used to facilitate flexion/extension alignment. Thefixation screws can then be advanced to touch the bone and mark theirlocation by passing standard drill bits or pins through the cannulationsin the fixation screws and into the bone. Then, the pattern and guidedevice are removed, the old implant removed, and the pattern devicerepositioned by means of the marked location of the fixation screws andthen fixed into place. Accordingly, the cuts for the new implant, andthus the new implant itself, are located and orientated based off of theold implant. This results in increased precision and awareness of thefinal implant location and orientation as well as potentialintraoperative time savings.

The particular example of the present invention discussed herein relatesto a prosthetic implant for attachment to a femur in the context oftotal knee arthroplasty, i.e., a femoral implant. However, it should bepointed out that the principles described herein may be applied to anyother applications where foreign or indigenous material is affixed toany other anatomic feature.

As shown generally in FIGS. 38 and 48, the implant apparatus of thepresent invention, generally indicated at 910, comprises curvilinearinterior fixation surface 920 as well as curvilinear exterior bearingsurface 940. Importantly, the implant of the present invention includescurvilinear surfaces extending from an anterior to a posterior area ofthe femur and/or implant, as is conventionally known, as well ascurvilinear surfaces extending from a medial to a lateral area of thefemur and/or implant to approximate the shape of natural femur. In otherwords, the fixation path (i.e., corresponding to the cutting path alongwhich the milling bit rides to resect the femur; indicated by arrow A inFIG. 38) as well as the fixation profile (as one proceeds along thecutting profile orthogonally to the cutting path; indicated by arrow Bin FIG. 38) are both predominantly curvilinear. As such, the cuttingprofile (arrow B) of the interior fixation surface 920 could include acurved or flat area 922 and another curved or flat area 924therebetween. Preferably, the outer areas 922 are flat or relativelyflat and the inner area 924 is curved to approximate the shape of anatural distal femur 912. It should be pointed out that the outer areas922 could be curved, and the inner area 924 could also be curved, butembodying differing radii of curvature. Additionally, it should bepointed out that the geometry of the internal fixation surface 920 ofthe implant 910 could be varied as desired. As such, any combination offlat surfaces and curvilinear surfaces could be used. As shown in FIG.48, and in more detail in FIGS. 48A, 48B, 48C and 48D, thecross-sectional thickness and mediolateral width of the implant of thepresent invention could vary along the implant 910. This varianceresults from merging a cutting tool to cut a bone, i.e., the implant 910closely resembles in size and shape the material removed from the bone.Accordingly, the cut starts as a point 925 and grows in depth and width.

The curvilinear bone surfaces necessary for proper fixation of such animplant 910 may be generated through the use of the curvilinear millingbit or form cutter and the curvilinear cutting path means discussed inthe previous related applications set forth herein, the entiredisclosures of which are expressly incorporated herein by reference.Basically, the milling bit has a profile resulting in form cutterconfiguration which is concentric about its longitudinal axis to effecta curvilinear cutting profile for receiving the implant of the presentinvention. One embodiment of such a form cutter is shown in FIGS. 35 and49. While it is possible to use multiple form cutters with differinggeometries and therefore an implant 910 with an internal geometry thatvaries along the cutting path from the anterior to the posterior of afemur, for the sake of intraoperative time savings, a singleanatomically optimal form cutter is preferable.

The form cutter shown in FIGS. 35 and 49 comprises a cutting guide 950having cutting paths 952 interconnected by member 954. A milling bit 960having cylindrical milling areas 962 at the ends, and a curved millingarea 964 at the center could be used. Of course, the milling areas carrycutting teeth. Spindles 961 interconnected at each end of the millingbit 960 could engage and ride the cutting path 952 of the cutting guide950. The milling bit 960 is then guided along the cutting path 952 bymeans of a handle. Importantly, the shape of the milling bit 960 couldbe varied as desired to create a resection having a desired cutting pathas well as a desired cutting profile.

The mediolateral cross-sectional internal geometry of such an implant910, and therefore the necessary resected bony surfaces of the femur,are consistent about the cutting path in a single form cutter system. Itshould be noted that the implant 910 may possess a notch 970 betweenmembers 972 (posterior femoral implant condyles) in the areasapproximately between the distal and posterior femoral condylar areas toaccommodate the posterior cruciate ligament, as well as for otherreasons. Because of the notch 970 between the posterior femoralcondyles, the form cutter may not cut any material in the notch 970.

Additionally, it may be advantageous to utilize a secondary form cutteras shown in FIG. 47 for use in creating a slot or slots in or near thedistal area of the femur before or after it has been resected. Such asecondary cutter 790 would include engagement means 792 for engagementwith driving means, and a shaft 794 carrying one or more cutters 796 forcutting slots into the femur through one or more of the resectedsurfaces thereof.

Through the inclusion of an additional or adjunct cutting path in thepattern means, it would be advantageous to utilize the form cutter tocreate the aforementioned slots in the distal femur to accommodate thefixation fins which may be molded as an integral part of the interiorsurface of the implant 910. An implant with fixation fins is shown inFIG. 50. The fins 980 would provide mediolateral fixation stability inaddition to that provided by the trochlear groove geometry of theimplant 910. Further, the fins also provide for additional surface areafor bony contact and ingrowth to increase implant fixation both incemented and cementless total knee arthroplasty.

FIG. 33 b shows another embodiment of a milling bit, generally indicatedat 754 for creating a curvilinear cutting path and curvilinear cuttingprofile in femur 756. In this embodiment, the transition from a firstcutting area 984 to a second cutting area 986 is continuous and smooth.This milling bit 754 also includes spindles 981 at the ends thereof forengagement with pattern means to guide the milling bit along a cuttingpath.

There are numerous advantages to the femoral component herein described.Foremost, it will allow for the thinnest implant cross-section possible(perhaps 3 mm to 6 mm in nominal thickness) and therefore necessitatethe removal of the least amount of viable osseous tissue. This isespecially critical in situations where the probability of revisionsurgery is high and the amount of viable bone available for revisionimplant fixation and apposition is a significant factor in the viabilityof the revision procedure. Since the form cutter configuration allowsfor similar amounts of tissue to be removed from the trochlear groove,the bony prominences surrounding the trochlear groove, the femoralcondyles, and the other articular surfaces of the femur, the externalgeometry of the femoral implant can be optimized for patellofemoralarticulation as well as tibiofemoral articulation. In essence, thekinematics of the artificial joint could be made to be as close aspossible to that of a healthy, natural knee joint.

In addition, the curvilinear geometry of the implant dramaticallydecreases the stress risers inherent in conventional rectilinear femoralimplants and allows for a thinner cross-sectional geometry whilepotentially increasing the resistance of the implant to mechanicalfailure under fatigue or impact loading. The implant could have arelatively consistent cross-sectional thickness throughout the implant,or it could be varied as desired.

The curvilinear geometry of the implant may also allow for anadvantageous reduction in the flexural rigidity of the implant which mayresult in avoidance of the “stress-shielding” inherent in rigid implantdesigns. Stress shielding being a phenomenon that may occur when livingbony tissue is prevented from experiencing the stresses necessary tostimulate its growth by the presence of a stiff implant. This phenomenonis analogous to the atrophy of muscle tissue when the muscle is notused, i.e., when a cast is placed on a person's arm the muscles in thatarm gradually weaken for lack of use.

Further, the curvilinear implant of the present invention could allowfor the use of a ceramic material in its construction. Since ceramicsare generally relatively weak in tension, existing ceramic implantdesigns contain very thick cross-sections which require a great deal ofbony material removal to allow for proper implantation. Utilization ofceramics in the curvilinear implant would not only allow for thesuperior surface properties of ceramic, but also avoid the excessivelythick cross-sections currently required for the use of the material.

The curvilinear implant of the present invention could result in a lessexpensive femoral implant because of the reduced amount of materialneeded for the implant, as well as an improved, more natural, and evenstronger knee replacement. It may desirable to vary the cross-section ofthe implant to assist in seating the implant, to increase the jointkinematics and to increase the strength and fit of the implant. Theimplant of the present invention could be fabricated of metal, plastic,or ceramic or any other material or combination thereof. Further, thethickness of the implants and the material required to fabricate theimplant could be reduced as the implants are adapted to increasinglycurvilinear surfaces. Also, it should be pointed out that such implantswith curvilinear implant surfaces require less bone to be removed toobtain a fit between the implant and the bone. Finally, it should benoted that curvilinear milling bits hereinbefore described would workwell for preparing a bone to receive an implant with curvilinearinterior implant surface.

Importantly, by using a milling bit having a curved profile, one can cuta femur to resemble the natural shape of the femur, i.e., the resectedfemur would include condylar bulges and a central notch. This wouldreduce the amount of bony material that must be removed from the femurwhile maintaining the structural integrity of the femur. Of course, anyprosthetic implant used for attachment to a femur resected by the curvedprofile milling bit would necessarily have an appropriately contouredinner fixation surface for mating with contoured surface of the femur.Additionally, it should be noted that the curved profile milling bitcould have one or more curvilinear bulges along the length thereof asshown in FIGS. 35 and 49, or alternatively, could have one or morebulges discretely formed along the length thereof.

The complete disclosures of the patents, patent applications andpublications cited herein are incorporated by reference in theirentirety as if each were individually incorporated. Variousmodifications and alterations to this invention will become apparent tothose skilled in the art without departing from the scope and spirit ofthis invention. It should be understood that this invention is notintended to be unduly limited by the illustrative embodiments andexamples set forth herein and that such examples and embodiments arepresented by way of example only with the scope of the inventionintended to be limited only by the claims set forth herein.

Shown in FIGS. 51, 52 and 53 is the femoral resection alignmentapparatus of the present invention, generally indicated at 1010. Thefemoral resection alignment apparatus 1010 includes a guide bodycomponent generally indicated at 1020, a rotating arm componentgenerally indicated at 1050, an extension rod component generallyindicated at 1060, and a tibia referencing component generally indicatedat 1070. These components cooperate to properly locate and orient drillholes 1080 on the distal femur for attaching a cutting guide device, notshown, for resecting the distal femur. As will be described, the cuttingguide employed may be one conventionally known in the art or the onedescribed in copending U.S. patent application Ser. No. 08/300,379,filed Sep. 2, 1994, the entire disclosure of which is incorporatedherein by reference.

As shown in FIG. 51, the guide body component generally indicated at1020 includes a guide body generally indicated at 1028 having tongues1022 extending from a lower end thereof The tongues 1022 include anupper surface 1024 for contacting and distracting the distal femur withrespect to the proximal tibia as hereinafter described. The tongues alsoinclude a lower surface 1026.

The guide body 1028 includes top surface 1030, sides 1032, front surface1034 and rear surface 1036. Extending through the guide body 1028 fromthe front 1034 towards the rear 1036 is rotating arm aperture 1038. Therotating arm aperture 1038 is positioned generally in the center ofguide body 1028, and accepts the rotating arm component as hereinafterdescribed. A rotating arm lock aperture 1040 extends from the top 1030of the guide body 1028 to the rotating arm aperture 1038 and rotatingarm lock screw 1042 is threadably engagable therewith. The rotating armlock screw 1042 may be turned down through the guide body 1028 tocontact the rotating arm component 1050 and lock the rotating armcomponent 1050 into a desired position.

Flanking the rotating arm aperture 1038 are drill hole apertures 1044which may be any desired shape and which extend through guide body 1028from the front 1034 to the rear 1036. The guide body 1028 also includesa body spacing aperture 1046 extending into the guide body 1028 from alower end thereof, and positioned central to the width of the guide body1028, typically between the parallel tongues 1024. The spacing aperture1046 prevents interference between the guide body 1028 and posteriorcruciate ligament and/or the tibia eminence during use.

Rotating arm component, generally indicated at 1050, includes acylindrical body 1052 having an extension rod aperture 1054 extendingtherethrough to receive extension rod component generally indicated at1060. Extending outwardly from the cylindrical body 1052 of rotating armcomponent 1050 are arms 1056 having drill screw apertures 1058positioned at outer ends thereof. Additionally, extending from thecylindrical body 1052 is arm attachment shaft 1059 which is sized to bereceived in the rotating arm aperture 1038 in guide body 1028. Armattachment shaft 1059 may be rotated within rotating arm aperture 1038of guide body 1028 and when in a desired position, can be locked intosuch position by tightening down rotating arm lock screw 1042 to contactthe arm attachment shaft 1059 within the rotating arm aperture 1038 ofguide body 1028.

An extension rod component, generally indicated at 1060, includes a rodshaft 1062 having threads 1063 formed thereon. The extension rodcomponent 1060 also includes a rod handle 1064 at an upper end of therod shaft 1062. The rod shaft 1062 extends through the extension rodaperture 1054 in rotating arm component 1050 and is threadably engagedtherewith. Rotation of the extension rod component 1060 by rotating therod handle 1064 causes the rotating arm component 1050 to travel up ordown the rod shaft 1062 in accordance with the direction of rotation ofthe extension rod component 1060.

The tibia referencing component, generally indicated at 1070, includesan upper surface 1072, a lower surface 1074, an extension rod attachmentmeans 1076 and a spacing channel 1078. The tibia referencing component1070 is interconnected with the extension rod component 1060 byreceiving a lower end of the rod shaft 1062, opposite the rod handle1064, in the extension rod attachment means 1076. Preferably, theextension rod attachment means 1076 interconnects the rod shaft 1062with the tibia referencing component 1070 and permits the rod shaft 1062to be freely rotated therein.

As seen in FIG. 52, in its operative position, the femoral resectionalignment device 1010 is positioned within the knee joint in flexionbetween the resected surface 1018 of tibia 1016 and the resected surface1014 of the femur 1012. The lower surface 1074 of the tibia referencingcomponent 1070 contacts the resected proximal surface 1018 of the tibia1016. The extension rod component 1060 extends up from the tibiareferencing component 1070, the rod shaft 1062 interconnected with theextension rod attachment means 1076 which holds the rod shaft 1062perpendicular to the tibia referencing component 1070. Riding on the rodshaft 1062 is rotating arm component 1050.

The arm attachment shaft 1059 of the rotating arm component 1050 isreceived by the guide body 1028 through the rotating arm aperture 1038,as shown in FIG. 51. The front 1034 of the guide body 1028 contacts theresected surface 1014 of the femur 1012 and is firmly attached thereto.The tongues 1022 extending from the guide body 1028 are positioned belowthe posterior condyles of the femur 1012 and the upper surfaces 1024 ofthe tongues 1022 contact the posterior condyles of the femur 1012.

In operation, the tibia referencing component 1070 contacts the resectedproximal surface 1018 of the tibia 1016 and the extension rod component1060 is actuated to lift the rotating arm component 1050 andaccordingly, the guide body 1028 and the tongues 1022 to distract thefemur 1012 with respect to the tibia 1016. The collateral ligaments 1015are accordingly drawn up to a tensioned position.

As best shown in FIG. 53, after the femur 1012 is distracted withrespect to the tibia 1016, it can be seen that the arms 1056 extendingfrom the rotating arm component 1050 are positioned parallel to thetibia referencing component 1070. Thus, an imaginary line extendingthrough drill screw apertures 1058 in arms 1056 is parallel to the tibiareferencing component 1070. After the femur is properly distracted fromthe tibia, the rotating arm component 1050 may be fixed with respect tothe guide body 1028 by screwing the rotating arm lock screw 1042 againstthe arm attachment shaft 1059 of the rotating arm component 1050, asshown in FIG. 51 a. Thereafter, any conventional drill may be extendedthrough the drill screw apertures 1058 in arms 1056 to drill holes intothe distal femur 1012. Accordingly, an imaginary line through the drillholes in the distal femur 1012 are parallel to the tibia referencingcomponent 1070 and hence to the resected surface 1018 of the tibia 1016.Thereafter, the femoral resection apparatus 1010 can be removed from itsposition.

As shown in FIG. 54, the drill holes 1080 in the femur 1012 arepositioned along an imaginary line A. Imaginary line A is parallel toimaginary line B that extends along the resected surface 1018 of thetibia 1016. Accordingly, the drill holes 1080 in the femur 1012 areproperly oriented based on the orientation of the resected surface 1018of the tibia 1016. Additionally, because the femoral resection alignmentdevice has been used to distract the femur 1012 with respect to thetibia 1016, the drill holes 1080 are properly located on the femur.

Thereafter, a conventional cutting guide device, not shown, can beattached to the femur using drill holes 1080 for receiving attachmentmeans to attach the cutting guide device at a proper location andorientation of the femur. Then, means for resecting the femur, as knownin the art, can be used to resection the femur. Because the drill holes1080 are properly located and oriented on the femur, and thus thecutting guide device is also properly located and oriented, the resectedfemur surfaces will likewise be properly located and oriented.

As shown in FIG. 55 and 56, the extension block component, generallyindicated at 1082, includes an extension block body 1084 and handle1086. Prior to utilizing the femoral resection alignment device toproperly locate and orient the drill holes in the femur, the leg is putinto extension and the extension block component 1082 is insertedbetween the resected surfaces 1014 and 1018 of the femur 1012 and tibia1016 respectively. The extension block body 1084 comes in various sizes.A typical block may be seventeen millimeters thick. The extension blockcomponent 1082, when in place between the tibia and femur, facilitatesligamentous release of collateral ligaments 1015 extending between thefemur 1012 and tibia 1016 on one side and the femur 1012 and fibula 1017on the other side to provide even tension on both sides of the kneejoint.

The method of using the femoral resection alignment apparatus of thepresent invention comprises the steps of: resecting the proximal tibia;moving the leg into extension; inserting the extension block componentbetween the resected proximal tibia and the femur (which may or may notbe partially resected); performing ligamentous release of collateralligaments to provide even tension of the collateral ligaments on bothsides of the knee joint; placing the leg into flexion; contacting thelower surface of the tibia referencing component against the resectedtibia; contacting the upper surface of the tongue of the guide bodyagainst the posterior condyles of the femur; distracting the femur fromthe tibia by actuating the rod shaft of the extension rod component tomove the rotating arm component and hence the guide body vertically awayfrom the tibia until the collateral ligaments are tensioned; fixedlyattaching the guide body to the femur; drilling drill holes into thefemur through drill screw apertures in the arms of the rotating armcomponent; removing the femoral resection alignment apparatus; andattaching a cutting guide device to the femur through the drill holes.

The femoral resection alignment method and apparatus is intended to workwith a conventional femur resection system by ensuring that the drillholes that are placed on the face of the distal femoral resection areparallel to the proximal tibial resection when the collateral ligamentsare balanced. Since the drill holes dictate the location and orientationof the cutting blocks, this device ensures that the rotating alignmentof the distal femoral resections and therefore, the rotating alignmentof the distal femoral prosthesis, is the same as the proximal tibialresection when the collateral ligaments are “balanced” (under equaltension).

In another embodiment of the present invention, as shown in FIGS. 57-59,the femoral resection alignment apparatus is adapted to work inconjunction with a system like the Femoral Resection apparatus describedin U.S. patent application Ser. No. 08/300,379 filed Sep. 2, 1994 whichincludes a pattern means positioned about the femur for guiding theresecting of the femur. Use of the present alignment device with FemoralResection Apparatus permits the location and orientation of the patternmeans to be directly controlled through the rotating arm component. Inthe configuration described in the previous patent application, theshaft of the rotating arm component terminates in the block that allowsit to be fastened to the femoral alignment positioning body.

Referring now to FIGS. 57-59, wherein corresponding elements of FIGS.51-53 are indicated with corresponding reference numerals with theaddition of 100. The shaft 1152 of the rotating arm component 1150extends through the block 1182 and is free to rotate in the block 1182.One end 1153 of the rotating arm component 1150 mates with the crossbar1200 and dictates the rotational alignment thereof, while the other endmates with the extension rod 1160 of the present invention. Since theextension rod 1160 is connected to tibial referencing plate 1170, therotating angle of crossbar 1200 and thereby the pattern device that maybe attached thereto, not shown, is based off of the proximal tibialresection.

More specifically, the apparatus shown in FIGS. 57-59 is generallyindicated at 1110 and includes a guide body 1120, a rotating armcomponent 1150, an extension rod component 1160, and a tibia referencingcomponent 1170. These components cooperate to properly locate and orienta cross bar 1200 for positioning a pattern device about the distal femurfor resecting the distal femur for guiding cutting means for resectingthe distal femur.

The guide body, generally indicated at 1120, includes a body 1128 havingtongues 1122 extending from a lower end thereof. The tongues 1122include an upper surface 1124 for contacting and distracting the distalfemur with respect to the proximal tibia. The tongues also include alower surface 1126.

The guide body 1128 includes top surface 1130, sides 1132, front surface1134 and rear surface 1136. The guide body further includes a channelextending into the body into the body 1128 from the top surface 1130.The channel is defined by side walls 1196 and bottom wall 1194 in guidebody 1128. The channel is sized to receive block 1182 through which therotating arm component 1150 extends. The block 1182 is verticallymoveable within the channel of the guide body 1128 and may be fixed intoa desired position by lock screws 1199 which extend through apertures1198 of the guide body 1122 to contact side walls 1184 of the block 1182to lock the block 1182 within the channel. Positioning of the block 1182within the channel of the guide body 1128 may be referenced by anumbered scale on the guide 1128.

The rotating arm component 1150 includes a shaft 1152, a keyed surface1153 for attachment to cross bar 1200 and an aperture 1154 for receivingan extension rod therethrough. A shaft 1152 extends through aperture1192 in block 1182 and can rotate with respect thereto.

The extension rod component, generally indicated at 1160, includes a rodshaft 1162 having threads 1163 formed thereon. Extension rod 1160 alsoincludes a rod handle 1164 at an upper end of the rod shaft 1162. Therod shaft 1162 extends through the aperture 1154 in the rotating armcomponent 1150 and is threadably engaged therewith. Rotation of theextension rod component 1160 by rotating the rod handle 1164 causes therotating arm component 1150 to travel up or down the rod shaft 1162 inaccordance with the direction of the rotation of the extension rodcomponent 1160. This causes the block 1182 to move vertically withrespect to the rod shaft 1162 and in turn causes the guide body 1120 tomove up and down with respect to the extension rod 1160.

The tibia referencing component, generally indicated at 1170, includesan upper surface 1172, a lower surface 1174, an extension rod attachmentmeans 1176 and a spacing channel 1178. The tibia referencing component1170 is interconnected with the extension rod component rod 1160 byattachment means 1176. Preferably, the extension rod attachment means1176 interconnects the tibia referencing component 1170 with the rodshaft 1162 and permits the rod shaft to be freely rotated therein.

As seen in its operative position in FIG. 58, the femoral resectionalignment device 1110 is positioned within the knee joint in flexionbetween resected surface 1018 of the tibia 1016 and the femur 1012. Thelower surface 1174 of the tibia referencing component 1170 contacts theresected proximal surface 1018 of the tibia 1016. The extension rodcomponent 1160 stands up from the tibia referencing component 1170, therod shaft 1162 interconnected with the extension rod attachment means1176 which holds the rod shaft 1162 perpendicular to the tibiareferencing component 1170. Riding on the rod shaft 1162 is rotating armcomponent 1150. The body 1152 of the rotating arm component 1150 isreceived by block 1182 which is locked into position within the guidebody 1128 by locking screws 1199 interconnected with the guide body1120. The tongues 1122 of the guide body 1128 are positioned below theposterior condyles of the femur 1012 and the upper surfaces 1124 of thetongues 1122 contact the posterior condyles of the femur.

In operation, the tibia referencing component contacts the resectedproximal surface 1018 of the tibia 1016 and the extension rod component1160 is actuated to lift the rotating arm component 1150 andaccordingly, the guide body 1128 and tongues 1122 to distract the femur1012 with respect to the tibia 1016. The collateral ligaments 1015 areaccordingly drawn up to a tensioned position.

As best shown in FIG. 59, after the femur 1012 is distracted withrespect to the tibia 1016, it can be seen that the rotating armcomponent 1150 rotates with the tibia referencing component 1160.Thereafter, as can be seen in FIG. 60, after the femur is distractedfrom the tibia and the tibia referencing component 1170 is placed on theresected tibia 1016, the rotating arm component 1150 is naturallyrotated to correspond to the pitch of the resected tibia. Thereafter,the crossbar 1200 can be placed onto the keyed surface 1153 of therotating arm component 1150 to track the rotational alignment of therotating arm component 1150 to properly rotate the crossbar 1200 withrespect to the resected tibia 1016. Thereafter, cutting guide devices,not shown, can be interconnected with the cross bar 1200 to extend alongthe sides of the femur. The cutting guides are thereby accuratelypositioned for to guide a cutting means resecting the distal femur.

Also as shown in FIG. 60, the block 1182 may have lock screws 1199attached thereto which extend through elongated apertures or slots 1198in the guide body 1128 to permit adjusting the block 1182 in the channelof the guide body 1128 and then locking the position thereof. Thisallows for adjustment and fixation of the anterior-posterior positioningof the pattern device, and for the posterior resection to alwaysparallel the proximal tibia cut.

Importantly, it is the overriding object of both embodiments of thepresent invention to provide a method and apparatus for locating andorienting the resections of the distal femur based on the resectedsurface of the proximal tibia. In both cases, this is achieved byputting the knee joint into flexion and distracting the femur withrespect to the tibia to tension the collateral ligaments which havealready been properly sized by means of ligamentous release. Thereafter,a cutting guide device, be it a conventional cutting guide device or thecutting guide device comprising the pattern device of Applicant'sprevious patent, is oriented with respect to the orientation of theresected proximal tibia. Other devices to accomplish this purpose areconsidered within the scope of the present invention.

With the proper use of the previously described system, extremelyaccurate and reproducible alignment and location of bone cuts areattainable. The preparation of femoral surfaces may be completed in anymanner known in the art before and after using the instrumentation ofthe present invention.

Modifications of the foregoing may be made without departing from thespirit and scope of the invention. What is desired to be protected byLetters Patents is set forth in the appended claims.

In the process of developing the basic instrumentation concept discussedin parent U.S. Pat. No. 5,514,139, it was necessary to attach thecutting guides to the femur in a very robust manner in order to preventdeflection or movement of the cutting guide during the cutting process.The concept utilized to avoid cutting guide movement involved acannulated screw which applied opposable compression to the medial andlateral sides of the femur while a fixation nail was driven through thecannulae to complete fixation. In the earliest cadaveric evaluations ofthe instrumentation, it was noted that the fixation thus attained wasrobust enough to allow the ‘patient’ to be lifted from the table usingthe guide. Somewhat accidentally, it was also noted that the fixation ofthe guide to the bone in this manner also avoided any errors in cuttingguide placement. Since the cannulated fixation screws were broughtdirectly into contact with the bone surfaces, the moment arm the pinscould be subjected too was minimized and thus prevented mal-alignment ofthe cutting guides. The teachings of the related parent applications aregenerally discussed herein with reference to FIGS. 61-65.

FIGS. 61A and 61B show the first step in this technique where theintramedullary rod 2030 is introduced into the IM canal of the femur2020 while the alignment guide 2040 and cutting guide 2050 are assembledand then adjusted to the proper relative locations and orientations.FIGS. 62A and 62B show the cutting guide 2050 and the alignment guide2040 positioned about the femur 2020. The cutting guide 2050 is thenfixed to the femur 2020 using cannulated fixation screws and fixationnails. The alignment guide 2040 and intramedullary rod 2030 are thenremoved. FIGS. 63A and 63B show the cutting guide 2050 fixed to thedistal femur 2020 (fixation nails not shown) and the milling tool 2060.FIG. 64 shows the milling tool 2060 and the milling handle 2062. FIGS.65A and 65B show the milling tool 2060 and milling handle 2062 properlyarticulated with the cutting guide 2050 prior to initiating the cuttingprocess. The cutting process includes attaching a driver (a DC or ACdrill) to the milling tool 2060 and to manually direct the milling tool2060 and milling handle 2062 through the cutting path 2052 of thecutting guide 2050.

This technique works well in cadaveric evaluations. Interestingly, thereis an inability of the milling tool to cut the collateral ligaments orthe posterior cruciate ligament, likely due to the amount of surfacearea of the milling tool in contact with the ligament. An oscillatingsawblade brings finely pointed teeth, teeth whose leading tips aredirected at 90 degrees to the ligament fibers, directly into contactwith the ligaments, and thus a very small force is required for the verysmall surface area of the teeth to be forced through the ligament.Another way of stating this is that the local pressure induced by theteeth is very high even when motivated by very small forces due theextremely small surface area of contact between the teeth and theligament. The milling tool, on the other hand, has teeth which areessentially smooth, and which have much larger areas in contact with theligament, and are oriented tangentially to the fibers and body of theligament so that even at the maximum force levels induced by manuallypushing the milling handle and milling tool into a ligament (perhaps 25to 50 lbs.), the ligaments are not cut.

It should be noted that conventional milling was used in evaluations.Conventional milling, in the case of this instrumentation, dictates thatthe milling bit rotates in the opposite of the direction from thecutting direction to maximize both control during cutting and thesmoothness of the resulting surfaces. Climb milling, the opposite ofconventional milling, is potentially problematic and may be avoided byutilizing a one way clutch between the milling tool and the drilldriving the milling tool thus avoiding even accidental use of climbmilling.

FIGS. 66-69 show a variation on the methods and apparatus of the parentapplications which improves the accuracy and ease of use of theinstruments. FIGS. 66A and 66B show the alignment guide 2140 connectedto a drill guide 2142. The drill guide 2142 has hole locators 2144 forlocating positioning hole(s) in the medial and lateral sides of thefemur 2020 that correspond to the fixation features (nubs or cannulatedscrews) of the cutting guide, as will be described.

FIGS. 67A and 67B show the drill guide 2142 located about the sides ofthe distal femur 2020. At this point a drill is used to drill throughthe hole locators 2144 in the drill guide 2142 to create positioninghole(s) in the medial and lateral sides of the femur. It should be notedthat it is possible to place only the distal-most positioning hole inthe femur using the drill guide 2142, and then to rely on anextramedullary reference to determine the appropriate flexion-extensionalignment for the anterior-most fixation point.

FIG. 68 shows the cutting guide 2150 of this embodiment, having sideplates 2152 with a cutting path described therein, and an upper bridge2154 interconnecting the cutting plates 2152. To position the cuttingguide 2150 on a femur to be resected 2020, the side plates are spreadapart to allow for the introduction of fixation nubs 2156 into thepositioning holes 2157 created previously in femur 2120. FIG. 69 showsthe fixation nubs 2156 engaged in the positioning holes 2157, andadditionally, cannulated fixation screws 2158 fixed to the medial andlateral sides of the femur. The step of cutting the distal femur 2020 isessentially identical to the techniques shown in FIG. 65.

FIG. 70 shows a milling tool 2160 and handle 2162 wherein the cuttingblade has a curvilinear profile instead of a linear profile. This allowsfor shaping the profile of the resection. FIG. 71 shows a cutting guide2250 with a curved cutting path 2252, so that a curved cutting path canbe used to resect the femur. Using the cutting guide 2250 with thecurved cutting path 2252, together with the curvilinear profile millingtool 2160 shown in FIG. 70 allows for the resected femur 2020 to have acurved profile and a curved path. Shown in FIG. 72 are examples of acortical femoral components 2170 with linear paths, with curved andlinear paths, with curved paths, and with curved paths and curvedprofiles.

Referring now to FIGS. 73-75, it can be seen that similar techniques canbe applied to the use of an oscillating sawblade and a conventionalcutting block. FIGS. 73A and 73B show a modified cutting guide 2350attached to the distal femur 2020 in a manner similar to the millingcutting guide 2150 shown in FIG. 69. FIGS. 74A and 74B show a distalresection cutting guide 2380 being attached to the cutting guide 2350 bypositioning the distal resection cutting guide 2380 in slot 2351. Anoscillating saw is inserted into the slot 2382 of the distal resectioncutting guide 2380 and the distal resection is completed. As shown inFIGS. 75A, 75B and 75C, after the completion of the distal resection andremoval of the distal resection cutting guide 2380, a 4 in 1 cuttingguide block 2390 can be inserted into slot 2353 until it contacts thedistal resection surface of the femur 2020. The remaining femoralresections could then be completed as is known in the art. Thistechnique provides and advantage over other 5 in 1 oscillating sawbladetechniques in two ways. First, the accuracy of cutting guide placementin significantly improved and second, the leading edges of the sawbladeslots in the cutting guides may be brought into direct contact with thebone to be cut thus avoiding excessive cantilevering of the sawbladeresulting in sub-optimal cuts.

FIG. 76 is a close up side view of the alignment guide and drill guideshown in FIG. 66. The alignment guide 2240 interconnects with the drillguide 2242. The drill guide includes a plurality of drill hole locators2244, 2344 and size markings. FIG. 77 is a back view of the alignmentguide 2024 and drill guide 2242 shown in FIG. 76. Also shown in FIG. 77are drill hole locators 2244, 2344, fixation drill 2247 and sizing rod2245 for extending through sizing apertures 2444. The sizing rod 2245can be placed from the medial side of the femur to the lateral side inthe exact position of the anterior-most tip of the implant correspondingto the size intended for that hole. In this way, the drill holes forcutting guide placement are directly linked to the anterior sizereference and the alignment guides reference of the posterior condylesthus minimizing any form of tolerance stacking and allowing for the easyimplementation of simultaneous anterior and posterior referencing andadjustment.

FIGS. 78-80 relate to method of ligament balancing using the cuttingguide 2250 shown in FIG. 71. Soft tissue balancing for TKA is consideredto be crucial in the use of mobile bearing designs. There-popularization of this technique has spurred the development andcommercialization of some very intricate instrumentation systems thatare very prone to surgeon misuse due to their complexity. Anotherdrawback of these systems is that they balance the tissues in flexionand extension, but do not allow continuous reference of the soft tissuebalance throughout the range of motion similar to that achieved by trialreduction. By creating the edges of the cutting guide 2250 (or even atrailing guide including no cutting guide or cutting guide attachmentfeatures) in a profile or geometry that simulates the geometry of theimplant and having that geometry act or articulate with a referencingmeans on the cut proximal tibia 2021 and reference bar 2022 attachedthereto, an effective trial reduction of soft tissue balance may beattained prior to any femoral resection.

The cutting guide surfaces of the cutting guide need not be coplanarwith the surfaces to be created in a bone, but may instead be parallel,but offset. Also the cutting guides may be located over the surfaces ofthe bone to be cut, but not necessarily located about the sides of theentire bone to be cut. As shown in FIG. 81 a cutting guide 2450 may beapplied to the tibia or other bones. In addition, the cutting guideshown in FIGS. 81 and 82 is intentional depicted as only being capableof completing the anterior portion of the tibial resection; this isintended to demonstrate that, when planar cuts are desired, the milledsurface can be used to guide the remaining resection of an oscillatingsawblade thus preserving the accuracy of the milling technique whileminimizing the precision errors of the oscillating sawblade.

Modifications of the foregoing may be made without departing from thespirit and scope of the invention. What is desired to be protected byLetters Patents is set forth in the appended claims.

1. A femoral prosthetic implant for attachment to a femur during a kneearthroplasty procedure, the femur having a long axis, the implantcomprising: an outer bearing surface having a condylar portion and apatellofemoral portion; an inner bone contact surface in back to backdisposition with the outer bearing surface, the inner bone contactsurface including a posterior contact surface, a distal contact surface,an anterior contact surface, and an anterodistal contact surfaceinterconnecting the anterior contact surface and the distal contactsurface, the distal contact surface having a proximally extendingfixation feature possessing at least one generally medially or laterallyfacing bone contacting surface, wherein the anterior contact surface isconfigured to diverge proximally away from the long axis of the femur;the posterior contact surface is configured to converge proximallytoward the long axis of the femur; a profile of the anterodistal contactsurface is curved when viewed in a medial to lateral direction; and atleast a portion of the posterior contact surface and the anteriorcontact surface converge toward one another at a point proximal of thedistal contact surface.
 2. The implant of claim 1 wherein the fixationfeature includes at least one fin-like structure with at least one bonecontacting surface extending in both an anterior to posterior directionand a proximal to distal direction.
 3. The implant of claim 2 whereinthe fixation feature includes a plurality of fin-like structures.
 4. Theimplant of claim 3 wherein at least one of the plurality of fin-likestructures is configured to operably abut at least one of a mediallyfacing resected bone surface and at least one of the plurality offin-like structures is configured to operably abut at least one of alaterally facing bone surface to provide medial-lateral fixationstability between the implant and the bone.
 5. The implant of claim 1wherein the anterior contact surface and the posterior contact surfaceare configured to achieve a fit with resected femoral bone surfaces whenthe distal contact surface is in contact with a resected femoral bonesurface without significant gaps between the contact surfaces and theresected femoral bone surface.
 6. The implant of claim 1 wherein theproximally extending fixation feature is formed as an integral part ofthe femoral implant.
 7. The implant of claim 1 wherein the implant ispart of a total knee arthroplasty implant.
 8. The implant of claim 1wherein at least a portion of the anterior contact surface has a linearprofile when viewed in a generally mediolateral direction.
 9. A femoralprosthetic implant for attachment to a femur during a knee arthroplastyprocedure, the femur having a long axis, the femoral implant comprising:an outer bearing surface having a condylar portion and a patellofemoralportion; an inner bone contact surface in back to back disposition withthe outer bearing surface, the inner contact surface including aposterior contact surface, a distal contact surface, an anterior contactsurface, and an anterodistal contact surface interconnecting theanterior contact surface and the distal contact surface, the inner bonecontact surface having a mediolaterally extending fixation profilecorresponding to a mediolaterally extending resection profile of cutsurfaces on the femur, a portion of the fixation profile including acontinuous, non-colinear cross-section including bone facing elementsconfigured to prevent motion between the implant and the femurmediolaterally by a material interference between the resected bone andthe inner bone contact surface in a medial-lateral direction, whereinthe anterior contact surface is configured to diverge proximally awayfrom the long axis of the femur; the posterior contact surface isconfigured to converge proximally toward the long axis of the femur; thefixation profile has a portion that extends inwardly to provide medialor lateral abutment of the inner bone contact surface with cut surfaceon the femur; and at least a portion of the posterior contact surfaceand the anterior contact surface converge toward one another at a pointproximal of the distal contact surface.
 10. The implant of claim 9wherein the distal contact surface has a proximally extending fixationfeature possessing at least one generally medially or laterally facingbone contacting surface configured to prevent medial-lateral motion ofthe implant with respect to the femur.
 11. The implant of claim 9wherein the bone facing elements includes at least one fin-likestructure with at least one bone contacting surface extending in both ananterior to posterior direction and a proximal to distal direction. 12.The implant of claim 11 wherein the bone facing elements include aplurality of fin-like structures.
 13. The implant of claim 12 wherein atleast one of the plurality of fin-like structures is configured tooperably abut at least one of a medially facing resected bone surfaceand at least one of the plurality of fin-like structures is configuredto operably abut at least one of a laterally facing bone surface toprovide medial-lateral fixation stability between the implant and thebone.
 14. The implant of claim 9 wherein the anterior contact surfaceand the posterior contact surface are configured to achieve a fit withresected femoral bone surfaces when the distal contact surface is incontact with a resected femoral bone surface without significant gapsbetween the contact surfaces and the resected femoral bone surface. 15.A femoral prosthetic implant for attachment to a femur during a kneearthroplasty procedure, the femur having a long axis, the implantcomprising: an outer bearing surface having a condylar portion and apatellofemoral portion; an inner bone contact surface in back to backdisposition with the outer bearing surface, the inner contact surfaceincluding a posterior contact surface, a distal contact surface, ananterior contact surface, and an anterodistal contact surfaceinterconnecting the anterior contact surface and the distal contactsurface, the inner bone contact surface configured to substantiallycontact resected surfaces of the femur corresponding to the inner bonecontact surface in a continuous predetermined manner, wherein theanterior contact surface is configured to diverge proximally away fromthe long axis of the femur; the posterior contact surface is configuredto converge proximally toward the long axis of the femur; a profile ofthe anterodistal contact surface is one of a curved profile, acurvilinear profile, or a linear profile when viewed in a medial tolateral direction; and at least a portion of the posterior contactsurface and a portion of the anterior contact surface converge towardone another at a point proximal of the distal contact surface.
 16. Theimplant of claim 15 wherein the distal contact surface has a proximallyextending fixation feature possessing at least one generally medially orlaterally facing bone contacting surface configured to preventmedial-lateral motion of the implant with respect to the femur.
 17. Theimplant of claim 15 wherein the inner contact surface includes at leastone fin-like structure with at least one bone contacting surfaceextending in both an anterior to posterior direction and a proximal todistal direction.
 18. The implant of claim 17 wherein the at least onefin-like structure includes a plurality of fin-like structures.
 19. Theimplant of claim 18 wherein at least one of the plurality of fin-likestructures is configured to operably abut at least one of a mediallyfacing resected bone surface and at least one of the plurality offin-like structures is configured to operably abut at least one of alaterally facing bone surface to provide medial-lateral fixationstability between the implant and the bone.
 20. The implant of claim 15wherein the anterior contact surface and the posterior contact surfaceare configured to achieve a fit with resected femoral bone surfaces whenthe distal contact surface is in contact with a resected femoral bonesurface without significant gaps between the contact surfaces and theresected femoral bone surface.